JP2022042315A - Zirconia powder, method of producing zirconia sintered body, and zirconia sintered body - Google Patents

Abstract

To provide zirconia powder that has excellent moldability, has a high sintered density, and can easily form a colored zirconia sintered body by a simple method.SOLUTION: The zirconia powder comprises zirconia containing yttria in an amount in a range of not lower than 2 mol% and not higher than 6 mol%, and one or more oxide selected from the group consisting of Group 4 to Group 9, Group 12 and Group 14, and lanthanoid. The volume of pores of the zirconia powder having a pore diameter of not larger than 200 nm is from 0.14 to 0.28 mL/g, and the relative molding density when molded at a molding pressure of 1 t/cm2 is from 44 to 55%.SELECTED DRAWING: None

Description

The present invention relates to zirconia powder, a method for producing a zirconia sintered body, and a zirconia sintered body.

Zirconia sintered bodies, especially square crystal phase zirconia sintered bodies, are being applied to household products such as cutlery and sports products such as golf shoe spikes due to their high strength and beautiful surface gloss after mirror polishing. Furthermore, it is expanding its application to decorative materials such as watch cases and accessories. In order to cope with such expansion of applications, zirconia having various colors is strongly demanded.

Against the background as described above, various color ceramics used for decorative parts have been proposed. For example, Patent Document 1 describes (a) ZrO ₂ 98 to 67 mol%, (b) stabilizer 1.5 to 26 mol%, and (c) MnO _4/3 0.3 to 1.5 mol%. (D) Al ₂ O ₃ 0.1 to 3.5 mol% and (e) one or more oxides 0.1 selected from the group consisting of CoO, Cr ₂ O _3, Fe ₂ O ₃ and TiO ₂ . A black zirconia sintered body consisting of ~ 2.0 mol% is disclosed.

Patent Document 2 describes a pink zirconia sintered body containing 0.5 to 2.0 mol% of Er ₂ O ₃ and 0.1 to 0.6 mol% of Zn O with respect to ZrO ₂ containing a stabilizer. Is disclosed.

Patent Document 3 describes a yellow zirconia sintered body containing 0.01 to 0.1 mol% of Pr _{6O 11 and} 0.1 to 0.6 mol% of ZnO with respect to ZrO ₂ containing a stabilizer. It has been disclosed.

The zirconia sintered body is manufactured by molding zirconia powder and then sintering the molded body. At this time, the zirconia powder is subjected to a stabilization treatment in advance. By performing the stabilization treatment, the crystal structure of the tetragonal system or the cubic system, which is the high temperature stable phase of the zirconia crystal, can be maintained up to room temperature. The stabilization treatment of zirconia crystals is usually carried out by dissolving oxides such as calcia, magnesia and yttrium in zirconia.
A sintered body made of zirconia formed only by a cubic crystal structure is widely used as a so-called fully stabilized zirconia (usually referred to as "stabilized zirconia") sintered body. Further, a sintered body containing zirconia having a tetragonal crystal structure is widely used as a partially stabilized zirconia sintered body. When the above-mentioned zirconia sintered body is obtained, the characteristics of the powder affect the handling and sintering characteristics at the time of manufacture. Therefore, the characteristics of the obtained zirconia sintered body are greatly affected by the characteristics of the zirconia powder as a raw material.

For example, Patent Document 4 contains 2 to 6 mol% of itria, has a pore volume of 200 nm or less and has a pore volume of 0.14 to 0.28 mL / g, and is described below when molded at a molding pressure of 1 t / cm ² . There is a disclosure of a zirconia powder having a relative molding density of 44 to 55% represented by the formula (1).
Relative molding density (%) = (molding density / theoretical sintering density) x 100 ... (1)
According to Patent Document 4, the zirconia powder has a high molding density when molded, and a sintered body having a sintering density of 99.5% or more with respect to the theoretical sintering density can be obtained. It is disclosed to that effect.

Japanese Unexamined Patent Publication No. 4-114964 Japanese Unexamined Patent Publication No. 4-2658 Japanese Unexamined Patent Publication No. 4-2657 International Publication No. 2017/170565

As in Patent Documents 1 to 3, colored zirconia sintered bodies (hereinafter, also referred to as color zirconia sintered bodies) and powders are conventionally known. On the other hand, conventionally, there is no example in which the moldability for obtaining a color zirconia sintered body has been examined in detail. As in Patent Documents 1 to 3, molding when obtaining a color zirconia sintered body generally requires a molding pressure of about 2 t / cm ² , and there is a problem that the process load is high.

When obtaining a color zirconia sintered body, it is usually necessary to pressurize the zirconia powder by press molding or the like to produce a green compact, that is, a molded body, and then sintered the molded body. In the molding process for making the body, the characteristics of the zirconia powder have a great influence. In order to obtain a color zirconia sintered body having high sintering density and strength of the sintered body, it is necessary to reduce defects and density unevenness in the molded body to make the molded body higher in density. In the press molding process, it is important to reduce the friction with the wall surface of the die during molding and to reduce the friction between the powder particles. If this friction is large, defects such as lamination and cracks will occur in the molded body, and if the friction is large, the molding pressure will not easily propagate between the particles, and it will not be possible to obtain a molded body with a high molding density. Pore remains in the body, making it difficult to increase the sintering density. In addition, when injection molding, extrusion molding, casting molding, etc. are used, distortion of the molded body, cracking of the sintered body due to uneven molding density, etc. occur, and when sheet molding is used, the molding density should be increased. In many cases, the sheet strength was lowered and the workability was deteriorated.

The present invention has been made in view of the above-mentioned problems, and an object thereof is a zirconia powder which is excellent in moldability, has a high sintering density, and can produce a color zirconia sintered body by a simple method. Is to provide. Another object of the present invention is to provide a method for producing a zirconia sintered body using the zirconia powder. Another object of the present invention is to provide a zirconia sintered body produced by using the zirconia powder.

As a result of diligent research to achieve the above object, the present inventors have controlled the degree of cohesion of the primary particles in a dispersed state of the oxide for coloring within a specific range. We have found that the object can be achieved and have completed the present invention.

That is, the zirconia powder according to the present invention is
With zirconia containing yttrium in the range of 2 mol% or more and 6 mol% or less,
Includes one or more oxides selected from the group consisting of Group 4-9, Group 12, Group 14 and lanthanoid elements.
The pore volume having a pore diameter of 200 nm or less is 0.14 to 0.28 mL / g, and the pore volume is 0.14 to 0.28 mL / g.
When molded at a molding pressure of 1 t / cm ² , the relative molding density represented by the following formula (1) is 44 to 55%.
Relative molding density (%) = (molding density / theoretical sintering density) x 100 ... (1)

According to the above configuration, since the pore volume having a pore diameter of 200 nm or less is 0.14 to 0.28 mL / g, it has a high molding density when molded. Therefore, the zirconia powder is suitable for various molding methods such as press molding, injection molding, casting molding, and sheet molding. Moreover, since the zirconia powder is easy to mass-produce, it has excellent cost competitiveness and can be applied to various uses. Further, since the relative molding density is 44 to 55%, a sintered body having a high sintering density can be obtained. Further, since it contains one or more oxides selected from the group consisting of Group 4 to Group 9, Group 12, Group 14, and lanthanoid elements, it can be a colored sintered body.
As described above, according to the zirconia powder according to the present invention, by controlling the degree of cohesion of the primary particles in a state where the oxide for coloring is dispersed within a specific range, the zirconia powder is excellent in moldability and highly baked. The color zirconia sintered body can be produced by a simple method having a cohesive density.

In the above configuration, the 4th to 9th groups are one or more selected from the group consisting of Ti, V, Cr, Mn, Fe, and Co, and the 12th group is Zn. It is preferable that the 14th group is Si and the lanthanoid element is at least one selected from the group consisting of Er, Tb, and Pr. In the case of coloring, there are a combination of elements and an addition amount suitable for the combination, which will be described later.

In the above configuration, the specific surface area is 5 to 20 m ² / g.
The average particle size is preferably 0.3 to 0.8 μm.

When the specific surface area of the zirconia powder is within the above range, it is easy to obtain a molded body having a high molding density, and it is easy to suppress a decrease in sinterability and sintering density.
Further, when the average particle size of the zirconia powder is in the above range, it is easy to obtain a molded body having a high molding density, and it is easy to suppress a decrease in sinterability and sintering density.

In the above configuration, it is preferable to include aluminum oxide.

When the zirconia powder contains alumina, the sinterability of the zirconia powder is improved, and it becomes easy to make the crystal structure uniform. Further, since the zirconia powder contains alumina, it is easy to suppress a decrease in the fracture toughness of the zirconia sintered body.

In the above configuration, the relative sintering density when molded at a molding pressure of 1 t / cm ² and sintered at 1450 ° C. for 2 hours is preferably 99.5% or more.

When the relative sintering density is 99.5% or more, it can be said that the sintering density is higher.

In the above configuration, Fe ₂ O ₃ is 0.4 to 1.0% by mass, CoO is 0.9 to 1.5% by mass, and Cr ₂ O ₃ is 1.0 to 1.6% by mass as the oxide. %, TiO ₂ is preferably contained in an amount of 0.5 to 0.9% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, as the oxide, CoO is contained in an amount of 0.9 to 1.5% by mass, Cr _{2O 3} is contained in an amount of 1.0 to 1.6% by mass, and MnO ₂ is contained in an amount of 0.8 to 1.4% by mass. Is preferable. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, it is preferable to contain ZnO in an amount of 0.15 to 0.35% by mass as the oxide. When the colorant is contained within the above range, preferable color development is obtained.

In the above structure, it is preferable that Cr ₂ O ₃ is contained in an amount of 0.02 to 0.1% by mass as the oxide. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is less than 0.005% by weight.
The oxide preferably contains MnO ₂ in an amount of 0.03 to 0.06% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 0.005% by mass or more and 2% by mass or less.
The oxide preferably contains MnO ₂ in an amount of 0.02 to 0.05% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 0.005% by mass or more and 2% by mass or less.
The oxide preferably contains MnO ₂ in an amount of 0.2 to 0.5% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 0.005% by mass or more and 2% by mass or less.
The oxide preferably contains Fe ₂ O ₃ in an amount of 0.12 to 0.40% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is less than 0.005% by weight.
The oxide preferably contains Fe ₂ O ₃ in an amount of 0.12 to 0.23% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 1% by mass or more and 3% by mass or less.
The oxide preferably contains CoO in an amount of 0.3 to 1.0% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 0.005% by mass or more and 2% by mass or less.
As the oxide, it is preferable to contain Pr ₆ O ₁₁ in an amount of 0.20 to 0.60% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 0.005% by mass or more and 2% by mass or less.
As the oxide, it is preferable to contain SiO ₂ in an amount of 0.03 to 0.30% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 1% by mass or more and 3% by mass or less.
The oxide preferably contains CoO in an amount of 0.3 to 1.0% by mass, Cr _{2O 3} in an amount of 0.05 to 0.25% by mass, and MnO ₂ in an amount of 0.03 to 0.2% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 1% by mass or more and 3% by mass or less.
As the oxide, it is preferable that CoO is contained in an amount of 0.2 to 0.8% by mass, Cr _{2O 3} is contained in an amount of 0.26 to 0.7% by mass, and MnO ₂ is contained in an amount of 0.21 to 0.4% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 1.5% by mass or more and 4% by mass or less.
As the oxide, Fe ₂ O ₃ is 0.1 to 0.5% by mass, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.3 to 0.9% by mass, and TiO ₂ is 0.2 to 0.2. It is preferably contained in an amount of 0.4% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 0.5% by mass or more and 2.5% by mass or less.
As the oxide, Fe ₂ O ₃ is 0.02 to 1% by mass, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.03 to 0.3% by mass, and TIO ₂ is 0.01 to 0%. It is preferably contained in an amount of 1% by mass. When the colorant is contained within the above range, preferable color development is obtained.

In the above configuration, the alumina content is 1% by mass or more and 3% by mass or less.
The oxide preferably contains 1.05 to 2% by mass of CoO. When the colorant is contained within the above range, preferable color development is obtained.

Further, the method for producing a zirconia sintered body according to the present invention is as follows.
Step X of molding the zirconia powder to obtain a molded body, and
It is characterized by having a step Y of sintering the molded body after the step X.

The zirconia powder has an oxide for coloring dispersed therein, has excellent moldability, and has a high sintering density. Therefore, according to the method for producing the zirconia sintered body using the zirconia powder, a color zirconia sintered body having a high sintering density can be produced.

Further, the zirconia sintered body according to the present invention contains one or more oxides selected from the group consisting of Group 4 to Group 9, Group 12, Group 14 and lanthanoid elements.
It is characterized by being obtained by the above-mentioned manufacturing method.

Since the zirconia sintered body according to the present invention is obtained by the method for producing the zirconia sintered body, it has a high sintering density. Further, it is a colored sintered body because it contains one or more oxides selected from the group consisting of Group 4 to Group 9, Group 12, Group 14, and lanthanoid elements. That is, according to the zirconia sintered body according to the present invention, it is possible to provide a colored zirconia sintered body that is colored and has a high sintering density.

In the above configuration, when the zirconia sintered body is colored black, Fe ₂ O ₃ is 0.4 to 1.0% by mass, CoO is 0.9 to 1.5% by mass, and Cr ₂ O ₃ is 1. It contains 0 to 1.6% by mass and TiO ₂ by 0.5 to 0.9% by mass, L ^* a ^* b ^* specified in the color system is -1 or more and 13 or less, and a ^* is- ^. It is preferably 7 or more and 7 or less, and b ^* is -8 or more and 6 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored in a black system of a different system, CoO is 0.9 to 1.5% by mass, Cr _{2O 3} is 1.0 to 1.6% by mass, and MnO ₂ is 0. .8 to 1.4% by mass, L ^* a ^* b ^* L ^* specified in the color system is 1 or more and 17 or less, a ^* is -9 or more and 5 or less, and b ^* is -8. It is preferably 6 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored white, it contains 0.15 to 0.35% by mass of ZnO, and L ^* a ^* b ^* defined by the color system is 80 or more and 96 or less ^. , A ^* is preferably -7 or more and 7 or less, and b ^* is preferably -6 or more and 8 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored gray, it contains 0.02 to 0.1% by mass of Cr ₂ O ₃ and has an L ^* a ^* b ^* L ^* specified in the color system of 30 or more. It is preferably 52 or less, a ^* is -5 or more and 8 or less, and b ^* is 0 or more and 20 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored gray, MnO ₂ is 0.03 to 0.03 under the condition that the alumina content is less than 0.005% by mass (the condition that substantially does not contain alumina). It contains 0.06% by mass, L ^* a ^* b ^* L ^* specified in the color system is 28 or more and 44 or less, a ^* is -3 or more and 8 or less, and b ^* is -8 or more and 8 or less. Is preferable. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored gray, it contains 0.02 to 0.05% by mass of MnO ₂ under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. , L ^* a ^* b ^* It is preferable that L ^* defined by the color system is 31 or more and 47 or less, a ^* is -4 or more and 12 or less, and b ^* is -9 or more and 7 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored black, it contains 0.2 to 0.5% by mass of MnO ₂ under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferable that L ^* a ^* b ^* defined by the color system is 1 or more and 23 or less, a ^* is -5 or more and 11 or less, and b ^* is -10 or more and 6 or less ^. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored brown, Fe ₂ O ₃ is 0.12 to 0.40% by mass under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. Including, it is preferable that L ^* defined by L ^* a ^* b ^* color system is 55 or more and 75 or less, a ^* is -2 or more and 17 or less, and b ^* is 18 or more and 40 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored brown, Fe ₂ O ₃ is added under the condition that the alumina content is less than 0.005% by mass (the condition that substantially does not contain alumina). Contains 12 to 0.23% by mass, L ^* a ^* b ^* L ^* specified in the color system is 41 or more and 61 or less, a ^* is 2 or more and 18 or less, and b ^* is 18 or more and 38 or less. It is preferable to have. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored blue, it contains 0.3 to 1.0% by mass of CoO under the condition that the alumina content is 1% by mass or more and 3% by mass or less, and L ^* a. ^* B ^* It is preferable that L ^* specified in the color system is 22 or more and 44 or less, a ^* is -10 or more and 7 or less, and b ^* is -50 or more and -28 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored yellowish, under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less, Pr ₆ O ₁₁ is 0.20 to 0.60% by mass. Including, it is preferable that L ^* defined by L ^* a ^* b ^* color system is 55 or more and 75 or less, a ^* is 4 or more and 20 or less, and b ^* is 40 or more and 60 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored white, it contains 0.03 to 0.30% by mass of SiO ₂ under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferable that L ^* a ^* b ^* defined by the color system is 77 or more and 97 or less, a ^* is -5 or more and 5 or less, and b ^* is -5 or more and 5 or less ^. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored in a deep blue color, CoO is 0.3 to 1.0% by mass and Cr _2O is under the condition that the alumina content is 1% by mass or more and 3% by mass or less. ₃ is included in an amount of 0.05 to 0.25% by mass and MnO ₂ is contained in an amount of 0.03 to 0.2% by mass, and L ^* a ^* b ^* defined by the color system is 13 or more and 33 or less ^. It is preferable that ^* is -12 or more and -2 or less, and b ^* is -29 or more and -19 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored in a deep blue color, CoO is 0.2 to 0.8% by mass and Cr _2O is under the condition that the alumina content is 1% by mass or more and 3% by mass or less. ₃ is contained in an amount of 0.26 to 0.7% by mass, MnO ₂ is contained in an amount of 0.21 to 0.4% by mass, and L ^* defined by the L ^* a ^* b ^* color system is 8 or more and 28 or less. It is preferable that ^* is -14 or more and -4 or less, and b ^* is -21 or more and -11 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored in a deep blue color, Fe ₂ O ₃ is 0.1 to 0.5 mass by mass under the condition that the alumina content is 1.5% by mass or more and 4% by mass or less. %, CoO is 1 to 2% by mass, Cr _{2O 3} is 0.3 to 0.9% by mass, TiO ₂ is 0.2 to 0.4% by mass, and is specified by L ^* a ^* b ^* color system. It is preferable that L ^* is 27 or more and 48 or less, a ^* is -6 or more and 4 or less, and b ^* is -10 or more and -1 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored in a deep blue color, Fe ₂ O ₃ is 0.02 to 1 mass by mass under the condition that the alumina content is 0.5% by mass or more and 2.5% by mass or less. %, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.03 to 0.3% by mass, TiO ₂ is 0.01 to 0.1% by mass, and is specified by L ^* a ^* b ^* color system. It is preferable that L ^* is 27 or more and 48 or less, a ^* is -6 or more and 4 or less, and b ^* is -10 or more and -1 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

In the above configuration, when the zirconia sintered body is colored in a deep blue color, it contains 1.05 to 2% by mass of CoO under the condition that the alumina content is 1% by mass or more and 3% by mass or less, and L ^* a ^*. b ^* It is preferable that L ^* defined by the color system is 27 or more and 48 or less, a ^* is -5 or more and 6 or less, and b ^* is -12 or more and -2 or less. When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

According to the present invention, it is possible to provide a zirconia powder which is excellent in moldability, has a high sintering density, and can produce a color zirconia sintered body by a simple method. Further, it is possible to provide a method for producing a zirconia sintered body using the zirconia powder. Further, it is possible to provide a zirconia sintered body produced by using the zirconia powder.

Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to these embodiments. In addition, in this specification, zirconia is a general thing, and contains an impurity metal compound of 10% by mass or less including hafnia. Further, in the present specification, the expressions "contains" and "contains" include the concepts of "contains", "contains", "substantially consists" and "consists only".

[Zirconia powder]
The zirconia powder according to this embodiment is
With zirconia containing yttrium in the range of 2 mol% or more and 6 mol% or less,
Includes one or more oxides selected from the group consisting of Group 4-9, Group 12, Group 14 and lanthanoid elements.
The pore volume having a pore diameter of 200 nm or less is 0.14 to 0.28 mL / g, and the pore volume is 0.14 to 0.28 mL / g.
When molded at a molding pressure of 1 t / cm ² , the relative molding density represented by the following formula (1) is 44 to 55%.

The zirconia powder contains primary particles containing zirconia as a main component. All or part of the primary particles aggregate to form secondary particles. That is, the zirconia powder contains primary particles that are not aggregated and secondary particles in which the primary particles are aggregated.
However, in the zirconia powder, the amount of primary particles that do not become secondary particles and exist in the state of non-aggregating primary particles is extremely small, for example, the entire primary particles (aggregating with non-aggregating primary particles). It is less than 1% by mass of the total of the primary particles that have become secondary particles. That is, the zirconia powder may contain a very small amount of non-aggregated primary particles, but most of them are composed of secondary particles.

The zirconia powder contains zirconia. The content of the zirconia is preferably 90% by mass or more, more preferably 92% by mass or more, still more preferably 94% by mass or more, and particularly preferably 94.3% by mass or more when the zirconia powder is 100% by mass. Is. The upper limit of the content of the zirconia is not particularly limited, but the content of the zirconia is preferably 97.5% by mass or less, more preferably 97.2% by mass or less, still more preferably 97% by mass or less, and particularly. It is preferably 96.9% by mass or less.

The zirconia powder contains 2 mol% or more and 6 mol% or less of itria with respect to the total mol amount of the zirconia. Ittoria acts as a stabilizer. Ittoria may be present in a solid solution with zirconia or as a mixture. From the viewpoint of elemental dispersibility during sintering, yttria preferably exists in a solid solution with zirconia. That is, yttria preferably exists in the form of yttria-stabilized zirconia. Since the content ratio of yttria is 2 mol% or more, it is possible to suppress an excessive ratio of the monoclinic phase in the sintered body of the zirconia powder. That is, it is possible to suppress the decrease in fracture toughness of the zirconia sintered body by suppressing the propagation of cracks due to the large volume expansion due to the phase transition from the tetragonal phase to the monoclinic phase.

The content of the yttrium is preferably 2 to 5 mol%, and particularly preferably 2 to 4 mol%. The content ratio of other preferable yttrium is 3 to 6 mol%, and in this range, a cubic phase having less optical anisotropy is formed, so that a zirconia sintered body having excellent translucency can be obtained. Can be done.

The zirconia powder may contain other components as a substitute for a part of yttrium. Examples of other components include alkaline earth metal oxides such as calcia and magnesia, and rare earth oxides such as ceria.

The zirconia powder can contain aluminum oxide (alumina), if necessary. The content of the alumina is not particularly limited, but may be 0.005 to 4.0% by mass, more preferably 0.005 to 2.0% by mass, based on the total mass of the zirconia powder. Can be done. When the zirconia powder contains alumina, the sinterability of the zirconia powder is improved, and it becomes easy to make the crystal structure uniform. Further, since the zirconia powder contains alumina, it is easy to suppress a decrease in the fracture toughness of the zirconia sintered body. Further, by adjusting the content of alumina, the translucency of the zirconia sintered body can be improved. The upper limit of the alumina content is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.4% by mass or less, and particularly preferably 0.4% by mass or less, based on the total mass of the zirconia powder. It is 0.3% by mass or less.

The form of alumina is not particularly limited, but alumina powder is preferable from the viewpoint of handleability at the time of preparation of zirconia powder and reduction of residual impurities.

When the alumina powder is added, the average particle size of the primary particles is not particularly limited, but can be 0.02 to 0.4 μm, more preferably 0.05 to 0.3 μm, still more preferably 0. It is 07 to 0.2 μm. The average particle size of the primary particles of alumina is a value measured by using a laser diffraction type particle size distribution measuring device "SALD-2300" (manufactured by Shimadzu Corporation).

The zirconia powder contains one or more oxides selected from the group consisting of Group 4-9, Group 12, Group 14 and lanthanoid elements. Zirconia firing obtained by sintering the zirconia powder because it contains at least one oxide selected from the group consisting of Group 4 to Group 9, Group 12, Group 14 and lanthanoid elements as a colorant. The body can be colored.

The 4th to 9th groups are preferably one or more selected from the group consisting of Ti, V, Cr, Mn, Fe, and Co. The Group 12 is preferably Zn. The Group 14 is preferably Si. The lanthanoid element is preferably one or more selected from the group consisting of Er, Tb, and Pr.

Specific examples of the oxide include TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , CoO, ZnO, SiO ₂ , Er ₂ O ₃ , and Tb ₄ O ₇ . , Pr ₆ O ₁₁ and the like. The oxide is preferably added as a mixture to the zirconia powder.

<First black system>
When the zirconia sintered body obtained by sintering is colored black, Fe ₂ O ₃ is 0.4 to 1.0% by mass and CoO is 0.9 to 1.5% by mass as the oxide. , Cr ₂ O ₃ is preferably contained in an amount of 1.0 to 1.6% by mass, and TiO ₂ is preferably contained in an amount of 0.5 to 0.9% by mass.
The content of Fe ₂ O ₃ is more preferably 0.5 to 0.9% by mass, further preferably 0.6 to 0.8% by mass.
The CoO content is more preferably 1.0 to 1.4% by mass, further preferably 1.1 to 1.3% by mass.
The content of Cr ₂ O ₃ is more preferably 1.1 to 1.5% by mass, further preferably 1.2 to 1.4% by mass.
The content of TiO ₂ is more preferably 0.55 to 0.85% by mass, further preferably 0.6 to 0.8% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Second black system>
When the zirconia sintered body obtained by sintering is colored into a black system different from the first black system, CoO is 0.9 to 1.5% by mass and Cr _2O as the oxide. It is preferable that ₃ is contained in an amount of 1.0 to 1.6% by mass and MnO ₂ is contained in an amount of 0.8 to 1.4% by mass.
The CoO content is more preferably 1.0 to 1.4% by mass, further preferably 1.1 to 1.3% by mass.
The content of Cr ₂ O ₃ is more preferably 1.1 to 1.5% by mass, further preferably 1.2 to 1.4% by mass.
The content of MnO ₂ is more preferably 0.9 to 1.3% by mass, further preferably 1.0 to 1.2% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Third black system>
When the zirconia sintered body obtained by sintering is colored into a black system different from the first and second black systems, the conditions under which the alumina content is 0.005% by mass or more and 2% by mass or less. Then, it is preferable to contain MnO ₂ in an amount of 0.2 to 0.5% by mass as the oxide.
The content of MnO ₂ is more preferably 0.25 to 0.45% by mass, still more preferably 0.3 to 0.4% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<First white system>
When the zirconia sintered body obtained by sintering is colored white, it is preferable to contain ZnO in an amount of 0.15 to 0.35% by mass as the oxide.
The ZnO content is more preferably 0.2 to 0.3% by mass, further preferably 0.22 to 0.28% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Second white system>
When the zirconia sintered body obtained by sintering is colored white, SiO ₂ is used as the oxide from 0.03 to 0.03 under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferably contained in an amount of 0.30% by mass.
The content of SiO ₂ is more preferably 0.05 to 0.2% by mass, further preferably 0.07 to 0.13% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<First gray system>
When the zirconia sintered body obtained by sintering is colored grayish, it is used as the oxide under the condition that the alumina content is less than 0.005% by mass (the condition that substantially does not contain alumina). , MnO ₂ is preferably contained in an amount of 0.03 to 0.06% by mass.
The content of MnO ₂ is more preferably 0.035 to 0.055% by mass, further preferably 0.04 to 0.05% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Second gray system>
When the zirconia sintered body obtained by sintering is colored gray, MnO ₂ is 0.02 as the oxide under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferably contained in an amount of up to 0.05% by mass.
The content of MnO ₂ is more preferably 0.025 to 0.045% by mass, further preferably 0.03 to 0.04% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Third gray system>
When the zirconia sintered body obtained by sintering is colored grayish, it is preferable that Cr ₂ O ₃ is contained in an amount of 0.02 to 0.1% by mass.
The content of Cr ₂ O ₃ is more preferably 0.04 to 0.08% by mass, further preferably 0.05 to 0.07% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<First brownish>
When the zirconia sintered body obtained by sintering is colored brown, Fe ₂ O ₃ is 0 as the oxide under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferably contained in an amount of .12 to 0.23% by mass.
The content of Fe ₂ O ₃ is more preferably 0.14 to 0.21% by mass, still more preferably 0.16 to 0.2% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Second brownish>
When the zirconia sintered body obtained by sintering is colored brown, it is used as the oxide under the condition that the alumina content is less than 0.005% by mass (the condition that substantially does not contain alumina). , Fe ₂ O ₃ is preferably contained in an amount of 0.12 to 0.23% by mass.
The content of Fe ₂ O ₃ is more preferably 0.14 to 0.21% by mass, still more preferably 0.16 to 0.2% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Third brown>
When the zirconia sintered body obtained by sintering is colored in a brownish color having a color deeper than that of the first brown, Fe ₂ under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferable to include O ₃ in an amount of 0.23 to 0.40% by mass.
The content of Fe ₂ O ₃ is more preferably 0.25 to 0.35% by mass, still more preferably 0.28 to 0.32% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Blue>
When the zirconia sintered body obtained by sintering is colored blue, it contains 0.3 to 1.0% by mass of CoO under the condition that the alumina content is 1% by mass or more and 3% by mass or less. It is good to let it.
The CoO content is more preferably 0.4 to 0.8% by mass, further preferably 0.5 to 0.7% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Yellow>
When the zirconia sintered body obtained by sintering is colored yellowish, Pr ₆ O ₁₁ is 0.20 to 0. Under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferable to include 60% by mass.
The content of Pr ₆ O ₁₁ is more preferably 0.30 to 0.50% by mass, further preferably 0.35 to 0.45% by mass.

<First deep blue system>
When the zirconia sintered body obtained by sintering is colored in a deep blue color, CoO is added as the oxide from 0.3 to 1 under the condition that the alumina content is 1% by mass or more and 3% by mass or less. It is preferable to contain 0% by mass, Cr _{2O 3} in an amount of 0.05 to 0.25% by mass, and MnO ₂ in an amount of 0.03 to 0.2% by mass.
The CoO content is more preferably 0.4 to 0.8% by mass, further preferably 0.5 to 0.6% by mass.
The content of Cr ₂ O ₃ is more preferably 0.08 to 0.2% by mass, further preferably 0.1 to 0.15% by mass.
The MnO content is more preferably 0.05 to 0.15% by mass, further preferably 0.08 to 0.12% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Second deep blue system>
When the zirconia sintered body obtained by sintering is colored in a deep blue color, the alumina content is 1% by mass or more and 3% by mass or less, and under the conditions, CoO is 0.2 to 0.2 to 2 as the oxide. It is preferable to contain 0.8% by mass, Cr _{2O 3} in an amount of 0.26 to 0.7% by mass, and MnO ₂ in an amount of 0.21 to 0.4% by mass.
The CoO content is more preferably 0.3 to 0.7% by mass, further preferably 0.35 to 0.5% by mass.
The content of Cr ₂ O ₃ is more preferably 0.3 to 0.5% by mass, further preferably 0.35 to 0.45% by mass.
The MnO content is more preferably 0.25 to 0.4% by mass, further preferably 0.28 to 0.32% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Third deep blue system>
When the zirconia sintered body obtained by sintering is colored in a deep blue color, Fe ₂ O ₃ is 0 as the oxide under the condition that the alumina content is 1.5% by mass or more and 4% by mass or less. It is preferable to contain 1 to 0.5% by mass, CoO by 1 to 2% by mass, Cr _{2O 3} by 0.3 to 0.9% by mass, and TiO ₂ by 0.2 to 0.4% by mass.
The content of Fe ₂ O ₃ is more preferably 0.2 to 0.4% by mass, further preferably 0.25 to 0.35% by mass.
The CoO content is more preferably 1.2 to 1.8% by mass, and even more preferably 1.3 to 1.6% by mass.
The content of Cr ₂ O ₃ is more preferably 0.4 to 0.7% by mass, further preferably 0.47 to 0.63% by mass.
The content of TiO ₂ is more preferably 0.23 to 0.36% by mass, further preferably 0.25 to 0.33% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Fourth deep blue system>
When the zirconia sintered body obtained by sintering is colored in a deep blue color, Fe ₂ O ₃ is used as the oxide under the condition that the alumina content is 0.5% by mass or more and 2.5% by mass or less. It is preferable to contain 0.02 to 1% by mass of CoO, 1 to 2% by mass of CoO, 0.03 to 0.3% by mass of Cr _{2O3 ,} and 0.01 to 0.1% by mass of TiO ₂ .
The content of Fe ₂ O ₃ is more preferably 0.03 to 0.08% by mass, further preferably 0.035 to 0.07% by mass.
The CoO content is more preferably 1.2 to 1.9% by mass, further preferably 1.4 to 1.7% by mass.
The content of Cr ₂ O ₃ is more preferably 0.05 to 0.2% by mass, further preferably 0.07 to 0.13% by mass.
The content of TiO ₂ is more preferably 0.02 to 0.09% by mass, further preferably 0.03 to 0.07% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

<Fifth deep blue system>
When the zirconia sintered body obtained by sintering is colored in a deep blue color, CoO is 1.05 to 2% by mass as the oxide under the condition that the alumina content is 1% by mass or more and 3% by mass or less. % Should be included.
The CoO content is more preferably 1.1 to 1.8% by mass, and even more preferably 1.2 to 1.4% by mass.
When the colorant is contained within the above range, preferable color development is obtained.

The zirconia powder has a pore volume of 0.14 to 0.28 mL / g with a pore diameter of 200 nm or less. The pore diameter referred to here indicates the size of the voids in the secondary particles formed by the aggregation of the primary particles.

When the pore volume of 200 nm or less is less than 0.14 mL / g, the agglutination of the primary particles is too strong, so that the secondary particles become coarse and the sinterability deteriorates. When the pore volume of 200 nm or less exceeds 0.28 mL / g, the aggregation of the primary particles is weak, so that the molding density of the molded body is low, and a sintered body having a high sintering density cannot be obtained. The pore volume of 200 nm or less is preferably 0.15 to 0.27 mL / g, more preferably 0.16 to 0.27 mL / g. Since the pore volume having a size of more than 200 nm indicates the voids between the secondary particles, such a large void has a low relationship with the degree of cohesion of the primary particles. The method for measuring the pore volume is the method described in the examples.

When the primary particle diameter of the zirconia powder of the present embodiment is 200 nm or less, the voids in the secondary particles formed by the aggregation of the primary particles, that is, the pore diameter between the primary particles tends to be 200 nm or less. By controlling the pore volume having a pore diameter of 200 nm or less, the degree of cohesion of the primary particles constituting the secondary particles can be controlled. When the value of the pore volume is small, the voids in the secondary particles are small and the aggregation of the primary particles is strong. Therefore, the molded product obtained from the powder having a small pore volume tends to have a high molding density because the primary particles constituting the secondary particles are densely packed.

The zirconia powder according to the present embodiment has a pore volume in a specific range as described above, so that the cohesiveness of the primary particles constituting the secondary particles is improved as compared with the conventionally known zirconia powder, and the zirconia powder is improved. The coarsening of the primary particles can also be suppressed. Therefore, controlling the pore volume having a pore diameter of 200 nm or less within the above range suppresses the coarsening of the primary particles while strengthening the aggregation of the primary particles themselves. As a result, the zirconia powder according to the present embodiment has excellent properties, and in particular, the zirconia powder is excellent in moldability.

The average particle size of the zirconia powder is preferably 0.3 μm or more and 0.8 μm or less. When the average particle size of the zirconia powder is in the above range, it is easy to obtain a molded body having a high molding density, and it is easy to suppress a decrease in sinterability and sintering density. Further, when the average particle size of the zirconia powder is in the above range, it is not necessary to lengthen the crushing time in the crushing step. Further, when the average particle size of the zirconia powder is 0.8 μm or less, the number of monoclinic phases in the powder does not increase too much, so that a sintered body having a high sintering density can be easily obtained. The average particle size of the zirconia powder is preferably 0.35 μm or more, more preferably 0.4 μm or more. The average particle size of the zirconia powder is preferably 0.75 μm or less, more preferably 0.7 μm or less.
The average particle size of the zirconia powder is a value measured using a laser diffraction type particle size distribution measuring device "SALD-2000" (manufactured by Shimadzu Corporation). More specifically, the method described in the examples is used. The average particle size described in the present specification is a value measured on a volume basis.

The specific surface area of the zirconia powder is preferably 5 m ² / g or more and 20 m ² / g or less. When the specific surface area of the zirconia powder is 5 m ² / g or more and 20 m ² / g or less, it is easy to obtain a molded body having a high molding density, and it is easy to suppress a decrease in sinterability and sintering density. The specific surface area of the zirconia powder is preferably 6 m ² / g or more, more preferably 6.5 m ² / g or more, and further preferably 7 m ² / g or more. The specific surface area of the zirconia powder is preferably 18 m ² / g or less, more preferably 15 m ² / g or less, still more preferably 13 m ² / g or less.
In the present specification, the specific surface area of the zirconia powder refers to the BET specific surface area, and is a value measured using a specific surface area meter "Macsorb", manufactured by Mountech.

The zirconia powder has a relative molding density of 44 to 55% when molded at a molding pressure of 1 t / cm ² . The relative molding density is preferably 45% or more, more preferably 46% or more, further preferably 47% or more, and particularly preferably 48% or more. The relative molding density is preferably 54% or less, more preferably 53% or less, further preferably 52% or less, particularly preferably 51% or less, and particularly preferably 50% or less.
Here, the relative molding density is a value calculated by the following formula (1).
Relative molding density (%) = (molding density / theoretical sintering density) x 100 ... (1)
Here, the theoretical sintering density (assumed to be ρ ₀ ) is a value calculated by the following equation (2-1).
ρ ₀ = 100 / [(Y / 3.987) + (100-Y) / ρz] ... (2-1)
However, X and Y are the itria concentration (mol%) and the alumina concentration (% by weight), respectively. Further, ρz is a value calculated by the following equation (2-2).
ρz = [124.25 (100-X) + 225.81X] / [150.5 (100 + X) A ^2C ] ... (2-2)
Here, A and C are values calculated by the following equations (2-3) and (2-3), respectively.
A = 0.5080 + 0.06980X / (100 + X) ... (2-3)
C = 0.5195-0.06180X / (100 + X) ... (2-4)
In formula (1), the theoretical sintering density varies depending on the composition of the powder. For example, the theoretical sintering density of yttria-containing zirconia is 6.112 g / cm 3 if the yttria content is 2 mol%, and 5.5 mol% if it is 6.092 g / cm ³ if it is ³ mol%. If there is, it is 6.045 g / cm ³ . It should be noted that these theoretical sintering densities take into account the amount of alumina of 0.25%. The molding density can be calculated by measuring the weight and volume of the molded body. When a colorant is added, the theoretical density can be calculated by the same calculation as in the case of adding alumina.

The zirconia powder is preferably molded at a molding pressure of 1 t / cm ² and sintered at 1450 ° C. for 2 hours, and the relative sintering density is preferably 99.5% or more. When the relative sintering density is 99.5% or more with respect to the theoretical sintering density, it can be said that the sintering density is higher.
The relative sintering density is a value calculated by the following formula (3).
The relative sintering density is ((%) = (sintering density / theoretical sintering density) × 100 ... (3)
The sintering density is a value obtained by measuring by the Archimedes method.

The zirconia powder according to the present embodiment has been described above.

[Manufacturing method of zirconia powder]
Hereinafter, an example of a method for producing zirconia powder will be described. However, the method for producing the zirconia powder of the present invention is not limited to the following examples.

The zirconia powder according to the present embodiment can be obtained by mixing the oxide with the powder as a base material before adding the colorant (the oxide). Specifically, the powder as the base material can be produced by the method for producing zirconia powder disclosed in Japanese Patent No. 6250242 (International Publication No. 2017/170565). As a more detailed method of mixing, it is preferable to disperse the mixture in pure water or the like to form a slurry and perform wet mixing. After wet mixing, it is preferably dried and sized through a sieve or the like. The mixing is preferably performed in such a manner that the powder as the base material and the oxide are not pulverized (the average particle size and the crystallite diameter do not change).

The method for producing the zirconia powder according to the present embodiment has been described above.

[Manufacturing method of zirconia sintered body]
Hereinafter, an example of a method for producing a zirconia sintered body will be described, but the present invention is not limited to the following examples.

The method for producing a zirconia sintered body according to the present embodiment is as follows.
Step X of molding the zirconia powder to obtain a molded body, and
After the step X, there is a step Y of sintering the molded body.

<Process X>
In the method for producing a zirconia sintered body according to the present embodiment, first, the zirconia powder is molded to obtain a molded body (step X). The molding pressure is not particularly limited, and may be 0.5 t / cm ² or more and 5 t / cm ² or less, 0.8 t / cm ² or more and 2 t / cm ² or less.

When molding the zirconia powder, a commercially available mold molding machine or a cold isotropic pressure pressurization method (CIP) can be adopted. Further, the zirconia powder may be temporarily molded by a mold molding machine and then main-molded by press molding such as CIP. Conventionally, when a molded body of color zirconia powder is produced, it is performed under high pressure conditions, but in the present embodiment, even within the above numerical range, a low molding pressure (for example, molding pressure 0.8 t / cm ² or more) is 1. It is possible to manufacture a molded body at 5 t / cm ² or less). In the present embodiment, by using the zirconia powder, a sintered body having high strength can be obtained even if a molded body is produced with such a low molding pressure.

<Step Y>
After the step X, the molded body is sintered (step Y). As a result, the zirconia sintered body according to the present embodiment can be obtained.

The heat treatment temperature and time at the time of sintering are not particularly limited, but are preferably about 1400 to 1550 ° C. for about 1 to 5 hours. The heat treatment atmosphere is preferably in the atmosphere or in an oxidizing atmosphere.

The method for producing the zirconia sintered body according to the present embodiment has been described above.

[Zirconia sintered body]
The zirconia sintered body according to this embodiment is
Contains one or more oxides selected from the group consisting of Group 4-9, Group 12, Group 14 and lanthanoid elements.
It is obtained by the method for producing zirconia powder.

The zirconia sintered body contains zirconia. The content of the zirconia is preferably 90% by mass or more, more preferably 92% by mass or more, still more preferably 94% by mass or more, and particularly preferably 94.3% by mass, when the zirconia sintered body is 100% by mass. That is all. The upper limit of the content of the zirconia is not particularly limited, but the content of the zirconia is preferably 97.5% by mass or less, more preferably 97.2% by mass or less, still more preferably 97% by mass or less, and particularly. It is preferably 96.9% by mass or less.

The zirconia sintered body contains yttria of 2 mol% or more and 6 mol% or less with respect to the total mol amount of the zirconia.

The content of the yttrium is preferably 2 to 5 mol%, and particularly preferably 2 to 4 mol%. The content ratio of other preferable ytria is 3 to 6 mol%, and in this range, a cubic phase having less optical anisotropy is formed, so that a zirconia sintered body having excellent translucency is obtained.

The zirconia sintered body can contain aluminum oxide (alumina).

The content of the alumina is not particularly limited, but can be 0.005 to 4.0% by mass, more preferably 0.005 to 2.0% by mass, based on the total mass of the zirconia sintered body. can do. When the zirconia sintered body contains alumina, the sinterability is improved and the crystal structure is easily made uniform. Further, when the zirconia sintered body contains alumina, it is easy to suppress a decrease in fracture toughness. Further, by adjusting the content of alumina, the translucency of the zirconia sintered body can be improved. The upper limit of the alumina content is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.4% by mass or less, particularly, with respect to the total mass of the zirconia sintered body. It is preferably 0.3% by mass or less.

The zirconia sintered body contains one or more oxides selected from the group consisting of Group 4 to Group 9, Group 12, Group 14, and lanthanoid elements. Since the zirconia sintered body is colored because it contains one or more oxides selected from the group consisting of Group 4 to Group 9, Group 12, Group 14 and lanthanoid elements as a colorant.

The 4th to 9th groups are preferably one or more selected from the group consisting of Ti, V, Cr, Mn, Fe, and Co. The Group 12 is preferably Zn. The Group 14 is preferably Si. The lanthanoid element is preferably one or more selected from the group consisting of Er, Tb, and Pr.

Specific examples of the oxide include TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , CoO, ZnO, SiO ₂ , Er ₂ O ₃ , and Tb ₄ O ₇ . , Pr ₆ O ₁₁ and the like.

<First black system>
When the zirconia sintered body is colored black, Fe ₂ O ₃ is 0.4 to 1.0% by mass, CoO is 0.9 to 1.5% by mass, and Cr ₂ O ₃ is 1 as the oxide. .0 to 1.6% by mass, TiO ₂ from 0.5 to 0.9% by mass, L ^* a ^* b ^* L ^* specified in the color system is -1 or more and 13 or less, and a ^* is It is preferably -7 or more and 7 or less, and b ^* is -8 or more and 6 or less.
The content of Fe ₂ O ₃ is more preferably 0.5 to 0.9% by mass, further preferably 0.6 to 0.8% by mass.
The CoO content is more preferably 1.0 to 1.4% by mass, further preferably 1.1 to 1.3% by mass.
The content of Cr ₂ O ₃ is more preferably 1.1 to 1.5% by mass, further preferably 1.2 to 1.4% by mass.
The content of TiO ₂ is more preferably 0.55 to 0.85% by mass, further preferably 0.6 to 0.8% by mass.
The L ^* is more preferably 4 or more and 8 or less, and further preferably 5 or more and 6.5 or less.
The a ^* is more preferably -2 or more and 2 or less, and further preferably -1 or more and 0 or less.
The b ^* is more preferably -3 or more and 1 or less, and further preferably -1.5 or more and -0.5 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Second black system>
When the zirconia sintered body is colored in a black system different from the first black system, CoO is 0.9 to 1.5% by mass and Cr ₂ O ₃ is 1.0 to 1 as the oxide. It contains 0.6% by mass and 0.8 to 1.4% by mass of MnO ₂ , L ^* a ^* b ^* L ^* specified in the color system is 1 or more and 17 or less, and a ^* is -9 or more and 5 It is preferable that b ^* is -8 or more and 6 or less.
The CoO content is more preferably 1.0 to 1.4% by mass, further preferably 1.1 to 1.3% by mass.
The content of Cr ₂ O ₃ is more preferably 1.1 to 1.5% by mass, further preferably 1.2 to 1.4% by mass.
The content of MnO ₂ is more preferably 0.9 to 1.3% by mass, further preferably 1.0 to 1.2% by mass.
The L ^* is more preferably 6 or more and 12 or less, and further preferably 8 or more and 9 or less.
The a ^* is more preferably -4 or more and 0 or less, and further preferably -2 or more and -1 or less.
The b ^* is more preferably -3 or more and 1 or less, and further preferably -1.5 or more and -0.5 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Third black system>
When the zirconia sintered body is colored into a black system different from the first and second black systems, it is used as the oxide under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. MnO ₂ is contained in an amount of 0.2 to 0.5% by mass, L ^* a ^* b ^* L ^* defined by the color system is 1 or more and 23 or less, a ^* is -5 or more and 11 or less, and b. It is preferable that ^* is -10 or more and 6 or less.
The content of MnO ₂ is more preferably 0.25 to 0.45% by mass, still more preferably 0.3 to 0.4% by mass.
The L ^* is more preferably 6 or more and 18 or less, and further preferably 10 or more and 14 or less.
The a ^* is more preferably 0 or more and 6 or less, and further preferably 2 or more and 4 or less.
The b ^* is more preferably -5 or more and 1 or less, and further preferably -3 or more and -1 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<First white system>
When the zirconia sintered body is colored white, it contains 0.15 to 0.35% by mass of ZnO as the oxide, and L ^* a ^* b ^* L ^* defined by the color system is 80 or more and 96 or less. It is preferable that a ^* is -7 or more and 7 or less, and b ^* is -6 or more and 8 or less.
The ZnO content is more preferably 0.2 to 0.3% by mass, further preferably 0.22 to 0.28% by mass.
The L ^* is more preferably 85 or more and 91 or less, and further preferably 87 or more and 89 or less.
The a ^* is more preferably -2 or more and 2 or less, and further preferably -1 or more and 0 or less.
The b ^* is more preferably -1 or more and 3 or less, and further preferably 1 or more and 2 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Second white system>
When the zirconia sintered body is colored white, it contains 0.03 to 0.30% by mass of SiO ₂ as the oxide under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It is preferable that L ^* a ^* b ^* defined by the color system is 77 or more and 97 or less, a ^* is -5 or more and 5 or less, and b ^* is -5 or more and 5 or less ^.
The content of SiO ₂ is more preferably 0.05 to 0.2% by mass, further preferably 0.07 to 0.13% by mass.
The L ^* is more preferably 82 or more and 91 or less, and further preferably 84 or more and 89 or less.
The a ^* is more preferably -3 or more and 3 or less, and further preferably -1 or more and 1 or less.
The b ^* is more preferably -3 or more and 3 or less, and further preferably 0 or more and 2 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<First gray system>
When the zirconia sintered body is colored gray, MnO ₂ is 0.03 as the oxide under the condition that the alumina content is less than 0.005% by mass (the condition that the alumina is not substantially contained). Including ~ 0.06% by mass, L ^* a ^* b ^* L ^* specified in the color system is 28 or more and 44 or less, a ^* is -3 or more and 8 or less, and b ^* is -8 or more and 8 or less. Is preferable.
The content of MnO ₂ is more preferably 0.035 to 0.055% by mass, further preferably 0.04 to 0.05% by mass.
The L ^* is more preferably 33 or more and 39 or less, and further preferably 35 or more and 37 or less.
The a ^* is more preferably 2 or more and 7 or less, and further preferably 4 or more and 6 or less.
The b ^* is more preferably -3 or more and 3 or less, and further preferably -1 or more and 1 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Second gray system>
When the zirconia sintered body is colored gray, it contains 0.02 to 0.05% by mass of MnO ₂ as the oxide under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. , L ^* a ^* b ^* It is preferable that L ^* defined by the color system is 31 or more and 47 or less, a ^* is -4 or more and 12 or less, and b ^* is -9 or more and 7 or less.
The content of MnO ₂ is more preferably 0.025 to 0.045% by mass, further preferably 0.03 to 0.04% by mass.
The L ^* is more preferably 36 or more and 42 or less, and further preferably 38 or more and 40 or less.
The a ^* is more preferably 1 or more and 7 or less, and further preferably 3 or more and 5 or less.
The b ^* is more preferably -4 or more and 2 or less, and further preferably -2 or more and 0 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Third gray system>
When the zirconia sintered body is colored gray, it contains 0.02 to 0.1% by mass of Cr ₂ O ₃ and L ^* a ^* b ^* L ^* specified by the color system is 30 or more and 52 or less. , A ^* is preferably −5 or more and 8 or less, and b ^* is preferably 0 or more and 20 or less.
The content of Cr ₂ O ₃ is more preferably 0.04 to 0.08% by mass, further preferably 0.05 to 0.07% by mass.
The L ^* is more preferably 35 or more and 47 or less, and further preferably 39 or more and 43 or less.
The a ^* is more preferably 0 or more and 6 or less, and further preferably 2 or more and 4 or less.
The b ^* is more preferably 5 or more and 15 or less, and further preferably 9 or more and 12 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<First brownish>
When the zirconia sintered body is colored brown, Fe ₂ O ₃ is 0.12 to 0.23 mass as the oxide under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. %, L ^* a ^* b ^* L ^* specified in the color system is 55 or more and 75 or less, a ^* is -2 or more and 14 or less, and b ^* is 18 or more and 40 or less.
The content of Fe ₂ O ₃ is more preferably 0.14 to 0.21% by mass, still more preferably 0.16 to 0.2% by mass.
The L ^* is more preferably 60 or more and 70 or less, and further preferably 63 or more and 67 or less.
The a ^* is more preferably 3 or more and 9 or less, and further preferably 5 or more and 7 or less.
The b ^* is more preferably 23 or more and 33 or less, and further preferably 26 or more and 30 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Second brownish>
When the zirconia sintered body is colored brown, Fe ₂ O ₃ is 0 as the oxide under the condition that the alumina content is less than 0.005% by mass (the condition that the alumina is not substantially contained). .12 to 0.23% by mass, including, L ^* a ^* b ^* L ^* specified in the color system is 41 or more and 61 or less, a ^* is 2 or more and 18 or less, and b ^* is 18 or more. It is preferably 38 or less.
The content of Fe ₂ O ₃ is more preferably 0.14 to 0.21% by mass, still more preferably 0.16 to 0.2% by mass.
The L ^* is more preferably 46 or more and 56 or less, and further preferably 49 or more and 53 or less.
The a ^* is more preferably 7 or more and 13 or less, and further preferably 9 or more and 11.5 or less.
The b ^* is more preferably 23 or more and 33 or less, and further preferably 27 or more and 30 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Third brown>
When the zirconia sintered body is colored in a brownish color having a deeper shade than the first brown color, Fe ₂ O ₃ is 0.23 to 0.23 to 2 under the condition that the alumina content is 0.005% by mass or more and 2% by mass or less. It contains 0.40% by mass, L ^* a ^* b ^* L ^* specified in the color system is 44 or more and 64 or less, a ^* is 1 or more and 17 or less, and b ^* is 20 or more and 40 or less. Is preferable.
The content of Fe ₂ O ₃ is more preferably 0.25 to 0.35% by mass, still more preferably 0.28 to 0.32% by mass.
The L ^* is more preferably 49 or more and 59 or less, and further preferably 52 or more and 56 or less.
The a ^* is more preferably 6 or more and 12 or less, and further preferably 8 or more and 10.5 or less.
The b ^* is more preferably 25 or more and 35 or less, and further preferably 28 or more and 32 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Blue>
When the zirconia sintered body is colored blue, it contains 0.3 to 1.0% by mass of CoO under the condition that the content of alumina is 1% by mass or more and 3% by mass or less, and L ^* a ^* b ^*. It is preferable that L ^* defined by the color system is 22 or more and 44 or less, a ^* is -10 or more and 7 or less, and b ^* is -50 or more and -28 or less.
The CoO content is more preferably 0.4 to 0.8% by mass, further preferably 0.5 to 0.7% by mass.
The L ^* is more preferably 27 or more and 39 or less, and further preferably 31 or more and 36 or less.
The a ^* is more preferably −5 or more and 2 or less, and further preferably -3 or more and 0 or less.
The b ^* is more preferably −45 or more and −33 or less, and further preferably −41 or more and −37 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Yellow>
When the zirconia sintered body is colored yellowish, it contains 0.20 to 0.60% by mass of Pr _{6O 11 under} the condition that the alumina content is 0.005% by mass or more and 2% by mass or less, and L ^* It is preferable that L ^* defined by a ^* b ^* color system is 55 or more and 75 or less, a ^* is 4 or more and 20 or less, and b ^* is 40 or more and 60 or less.
The content of Pr ₆ O ₁₁ is more preferably 0.30 to 0.50% by mass, further preferably 0.35 to 0.45% by mass.
The L ^* is more preferably 60 or more and 70 or less, and further preferably 63 or more and 67 or less.
The a ^* is more preferably 6 or more and 18 or less, and further preferably 9 or more and 13 or less.
The b ^* is more preferably 43 or more and 57 or less, and further preferably 47 or more and 54 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<First deep blue system>
When the zirconia sintered body is colored in a deep blue color, CoO is 0.3 to 1.0% by mass and Cr _2O as the oxide under the condition that the alumina content is 1% by mass or more and 3% by mass or less. ₃ is included in an amount of 0.05 to 0.25% by mass and MnO ₂ is contained in an amount of 0.03 to 0.2% by mass, and L ^* a ^* b ^* defined by the color system is 13 or more and 33 or less ^. It is preferable that ^* is -12 or more and -2 or less, and b ^* is -29 or more and -19 or less.
The CoO content is more preferably 0.4 to 0.8% by mass, further preferably 0.5 to 0.6% by mass.
The content of Cr ₂ O ₃ is more preferably 0.08 to 0.2% by mass, further preferably 0.1 to 0.15% by mass.
The MnO content is more preferably 0.05 to 0.15% by mass, further preferably 0.08 to 0.12% by mass.
The L ^* is more preferably 16 or more and 30 or less, and further preferably 20 or more and 26 or less.
The a ^* is more preferably -11 or more and -3 or less, and further preferably -9 or more and -5 or less.
The b ^* is more preferably −28 or more and −20 or less, and further preferably −26 or more and −22 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Second deep blue system>
When the zirconia sintered body is colored in a deep blue color, CoO is 0.2 to 0.8% by mass and Cr as the oxide under the conditions that the alumina content is 1% by mass or more and 3% by mass or less. _{2O 3} is contained in an amount of 0.26 to 0.7% by mass, MnO ₂ is contained in an amount of 0.21 to 0.4% by mass, and L ^* a ^* b ^* L ^* defined by the color system is 8 or more and 28 or less. , A ^* is preferably -14 or more and -4 or less, and b ^* is preferably -21 or more and -11 or less.
The CoO content is more preferably 0.3 to 0.7% by mass, further preferably 0.35 to 0.5% by mass.
The content of Cr ₂ O ₃ is more preferably 0.3 to 0.5% by mass, further preferably 0.35 to 0.45% by mass.
The MnO content is more preferably 0.25 to 0.4% by mass, further preferably 0.28 to 0.32% by mass.
The L ^* is more preferably 11 or more and 25 or less, and further preferably 14 or more and 22 or less.
The a ^* is more preferably -13 or more and -5 or less, and further preferably -11 or more and -7 or less.
The b ^* is more preferably -20 or more and -12 or less, and further preferably -18 or more and -14 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Third deep blue system>
When the zirconia sintered body is colored in a deep blue color, Fe ₂ O ₃ is 0.1 to 0.5 mass by mass as the oxide under the condition that the alumina content is 1.5% by mass or more and 4% by mass or less. %, CoO is 1 to 2% by mass, Cr _{2O 3} is 0.3 to 0.9% by mass, TiO ₂ is 0.2 to 0.4% by mass, and is specified by L ^* a ^* b ^* color system. It is preferable that L ^* is 27 or more and 48 or less, a ^* is -6 or more and 4 or less, and b ^* is -10 or more and -1 or less.
The content of Fe ₂ O ₃ is more preferably 0.2 to 0.4% by mass, further preferably 0.25 to 0.35% by mass.
The CoO content is more preferably 1.2 to 1.8% by mass, and even more preferably 1.3 to 1.6% by mass.
The content of Cr ₂ O ₃ is more preferably 0.4 to 0.7% by mass, further preferably 0.47 to 0.63% by mass.
The content of TiO ₂ is more preferably 0.23 to 0.36% by mass, further preferably 0.25 to 0.33% by mass.
The L ^* is more preferably 30 or more and 45 or less, and further preferably 34 or more and 40 or less.
The a ^* is more preferably -5 or more and 3 or less, and further preferably -3 or more and 1 or less.
The b ^* is more preferably -9 or more and -2 or less, and further preferably -7 or more and -4 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Fourth deep blue system>
When the zirconia sintered body is colored deep blue, Fe ₂ O ₃ is 0.02 to 1 mass as the oxide under the condition that the alumina content is 0.5% by mass or more and 2.5% by mass or less. %, CoO is 1 to 2% by mass, Cr _{2O 3} is 0.03 to 0.3% by mass, TiO ₂ is 0.01 to 0.1% by mass, and is specified by L ^* a ^* b ^* color system. It is preferable that L ^* is 27 or more and 48 or less, a ^* is -6 or more and 4 or less, and b ^* is -10 or more and -1 or less.
The content of Fe ₂ O ₃ is more preferably 0.03 to 0.08% by mass, further preferably 0.035 to 0.07% by mass.
The CoO content is more preferably 1.2 to 1.9% by mass, further preferably 1.4 to 1.7% by mass.
The content of Cr ₂ O ₃ is more preferably 0.05 to 0.2% by mass, further preferably 0.07 to 0.13% by mass.
The content of TiO ₂ is more preferably 0.02 to 0.09% by mass, further preferably 0.03 to 0.07% by mass.
The L ^* is more preferably 30 or more and 45 or less, and further preferably 34 or more and 40 or less.
The a ^* is more preferably −5 or more and 3 or less, and further preferably −2 or more and 2 or less.
The b ^* is more preferably -9 or more and -2 or less, and further preferably -7 or more and -4 or less.
When the oxide is contained within the above range, L ^* , a ^* , and b ^* defined by the L ^* a ^* b ^* color system can easily be within the above numerical range, and preferable color development is obtained.

<Fifth deep blue system>
When the zirconia sintered body is colored in a deep blue color, it contains 1.05 to 2% by mass of CoO as the oxide under the condition that the alumina content is 1% by mass or more and 3% by mass or less, and L ^* a ^*. b ^* It is preferable that L ^* defined by the color system is 27 or more and 48 or less, a ^* is -5 or more and 6 or less, and b ^* is -12 or more and -2 or less.
The CoO content is more preferably 1.1 to 1.8% by mass, and even more preferably 1.2 to 1.4% by mass.
The L ^* is more preferably 30 or more and 45 or less, and further preferably 35 or more and 41 or less.
The a ^* is more preferably −5 or more and 3 or less, and further preferably −2 or more and 2 or less.
The b ^* is more preferably -11 or more and -3 or less, and further preferably -9 or more and -5 or less.

The L ^* a ^* b ^* color system is a color space recommended by the International Commission on Illumination (CIE) in 1976, and is a color space called the CIE1976 (L ^* a ^* b ^* ) color system. It means that. The L ^* a ^* b ^* color system is specified in JIS Z 8729 in the Japanese Industrial Standards. In the present specification, the values of L ^* , a ^* , and b ^* (measurement of color tone) are obtained by adjusting the zirconia sintered body to a thickness of 3 mm and using a diamond paste containing diamond abrasive grains having a particle size of 3 μm or less. The measured value after mirror polishing.

The zirconia sintered body preferably has a sintering density of 99.5% or more with respect to the theoretical sintering density. When the sintering density is 99.5% or more with respect to the theoretical sintering density, it can be said that the sintering density is higher.

The zirconia sintered body according to the present embodiment has been described above.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The zirconia powders obtained in Examples and Comparative Examples contained hafnium oxide in an inevitable impurity in an amount of 1.3 to 2.5% by mass with respect to zirconium oxide (calculated by the following formula (X)). There is.
<Equation (X)>
([Mass of hafnium oxide] / ([Mass of zirconium oxide] + [Mass of hafnium oxide])) × 100 (%)

[Preparation of zirconia powder and zirconia sintered body]
(Example 1)
Sodium sulfate powder was dissolved in ion-exchanged water to obtain a 5% by mass solution of sodium sulfate. The obtained sodium sulfate solution was heated and maintained at 85 ° C.
On the other hand, the zirconium oxychloride solution was adjusted so as to contain 1% by mass of zirconium in terms of zirconia, heated, and maintained at 85 ° C. The total amount of zirconia was 100 g.
Next, a basic zirconium sulfate slurry was obtained by adding 1000 g of a sodium sulfate solution kept at a constant temperature at 85 ° C. to a zirconium oxychloride solution maintained at a constant temperature at 85 ° C. for 10 seconds with stirring. A yttrium chloride solution was added thereto so that the amount of yttrium was 3.0 mol% with respect to zirconia, and then neutralization was performed with sodium hydroxide to obtain a hydroxide.
After the hydroxide is filtered and washed with water, the hydroxide is fired in an electric furnace at a firing temperature of 1000 ° C. to obtain an oxide (zirconia), and then the alumina powder having an average particle diameter of 0.1 μm is oxidized. 0.25% by mass of Fe ₂ O ₃ powder as a colorant, 1.2% by mass of CoO powder, 1.3% by mass of Cr ₂ O ₃ powder, and TiO ₂ powder as a colorant. 0.7% by mass was added, and a wet ball mill using water as a dispersion medium was pulverized and mixed for 30 hours. The obtained slurry was dried at a constant temperature at 120 ° C. to obtain a zirconia powder according to Example 1.

8 g of the obtained zirconia powder was tentatively molded with a mold having a diameter of 25 mm, and molded at a molding pressure (hydrostatic pressure) of 1 t / cm ² . The molding density of the molded body was calculated by measuring the weight and volume. The obtained molded body was sintered at 1450 ° C. for 2 hours to obtain a zirconia sintered body according to Example 1.

(Examples 2 to 19)
The zirconia powder according to Examples 2 to 19 was obtained in the same manner as in Example 1 except that the amount of itria, the amount of alumina powder, the amount of colorant, and the firing temperature were changed as shown in Table 1. rice field. Further, in the same manner as in Example 1, zirconia sintered bodies according to Examples 2 to 19 were obtained.

[Measurement of composition of zirconia powder]
The composition (oxide equivalent) of the zirconia powder of the examples was analyzed using ICP-AES ("ULTIMA-2" manufactured by HORIBA). It is shown in Table 1.

[Measurement of pore volume]
For the zirconia powder of the example, the pore distribution was obtained by the mercury intrusion method using a pore distribution measuring device (manufactured by "Autopore IV 9500" Micromeritics). The measurement conditions were as follows.
<Measurement conditions>
Measuring device: Pore distribution measuring device (Micromeritics Autopore IV9500)
Measurement range: 0.0036 to 10.3 μm
Number of measurement points: 120 points Mercury contact angle: 140 degrees
Mercury surface tension: 480 dyne / cm

Using the obtained pore distribution, the pore volume in the range of 200 nm or less was determined. The results are shown in Table 2.

[Average particle size of zirconia powder]
The average particle size of the zirconia powder of the example was measured using a laser diffraction type particle size distribution measuring device "SALD-2000" (manufactured by Shimadzu Corporation). More specifically, 0.15 g of a sample and 40 ml of a 0.2% sodium hexametaphosphate aqueous solution are placed in a 50 ml beaker and dispersed in a desktop ultrasonic cleaner "W-113" (manufactured by Honda Electronics Corporation) for 5 minutes. After that, it was put into an apparatus (laser diffraction type particle size distribution measuring apparatus (“SALD-2000” manufactured by Shimadzu Corporation)) for measurement. The results are shown in Table 2.

[Measurement of specific surface area of zirconia powder]
The specific surface area of the zirconia powder of the example was measured by the BET method using a specific surface area meter (manufactured by "Macsorb" Mountech). The results are shown in Table 2.

[Relative molding density when molding at a molding pressure of 1 t / cm ² ]
The zirconia powder of the example was molded at a molding pressure of 1 t / cm ² , and the relative molding density was calculated by the following formula (1).
Relative molding density (%) = (molding density / theoretical sintering density) x 100 ... (1)
Here, the theoretical sintering density (assumed to be ρ ₀ ) is a value calculated by the following equation (2-1).
ρ ₀ = 100 / [(Y / 3.987) + (100-Y) / ρz] ... (2-1)
However, X and Y are the itria concentration (mol%) and the alumina concentration (% by weight), respectively. Further, ρz is a value calculated by the following equation (2-2).
ρz = [124.25 (100-X) + 225.81X] / [150.5 (100 + X) A ^2C ] ... (2-2)
Here, A and C are values calculated by the following equations (2-3) and (2-3), respectively.
A = 0.5080 + 0.06980X / (100 + X) ... (2-3)
C = 0.5195-0.06180X / (100 + X) ... (2-4)
In formula (1), the theoretical sintering density varies depending on the composition of the powder. For example, the theoretical sintering density of yttria-containing zirconia is 6.112 g / cm 3 if the yttria content is 2 mol%, and 5.5 mol% if it is 6.092 g / cm ³ if it is ³ mol%. If there is, it is 6.045 g / cm ³ . It should be noted that these theoretical sintering densities take into account the amount of alumina of 0.25%. The molding density was calculated by measuring the weight and volume of the molded body. When the colorant was added, the theoretical density was calculated by the same calculation as when the alumina was added.

[Relative sintering density when molding at a molding pressure of 1 t / cm ² and sintering at 1450 ° C. for 2 hours]
The relative sintering density of the zirconia sintered body of the example was determined according to the formula (3).

Relative sintering density (%) = (sintering density / theoretical sintering density) x 100 ... (3)
The sintering density was measured by the Archimedes method.

[Color tone of sintered body]
After adjusting the thickness of the zirconia sintered body of the example to 3 mm, mirror polishing was performed using an automatic polishing machine (“Ecomet 250” manufactured by BUEHLER). A diamond paste containing diamond abrasive grains having a particle size of 3 μm was used for finishing the mirror polishing. Then, the color tone of the obtained sintered body was measured using a color difference meter (trade name: CM-3500d, manufactured by Konica Minolta Co., Ltd.). The results are shown in Table 1.

Claims (42)

With zirconia containing yttrium in the range of 2 mol% or more and 6 mol% or less,
Includes one or more oxides selected from the group consisting of Group 4-9, Group 12, Group 14 and lanthanoid elements.
The pore volume having a pore diameter of 200 nm or less is 0.14 to 0.28 mL / g, and the pore volume is 0.14 to 0.28 mL / g.
A zirconia powder characterized by having a relative molding density of 44 to 55% represented by the following formula (1) when molded at a molding pressure of 1 t / cm ² .
Relative molding density (%) = (molding density / theoretical sintering density) x 100 ... (1) The 4th to 9th groups are one or more selected from the group consisting of Ti, V, Cr, Mn, Fe, and Co.
The 12th group is Zn, and the group 12 is Zn.
The 14th group is Si,
The zirconia powder according to claim 1, wherein the lanthanoid element is at least one selected from the group consisting of Er, Tb, and Pr. The specific surface area is 5 to 20 m ² / g,
The zirconia powder according to claim 1 or 2, wherein the average particle size is 0.3 to 0.8 μm. The zirconia powder according to any one of claims 1 to 3, which comprises aluminum oxide. The one according to any one of claims 1 to 4, wherein the relative sintering density when molded at a molding pressure of 1 t / cm ² and sintered at 1450 ° C. for 2 hours is 99.5% or more. Zirconia powder. As the oxide, Fe ₂ O ₃ is 0.4 to 1.0% by mass, CoO is 0.9 to 1.5% by mass, Cr ₂ O ₃ is 1.0 to 1.6% by mass, and TIO ₂ is used. The zirconia powder according to any one of claims 1 to 5, which comprises 0.5 to 0.9% by mass. The oxide is characterized by containing 0.9 to 1.5% by mass of CoO, 1.0 to 1.6% by mass of Cr _{2O 3} , and 0.8 to 1.4% by mass of MnO ₂ . The zirconia powder according to any one of claims 1 to 5. The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains ZnO in an amount of 0.15 to 0.35% by mass. The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains Cr _{2O 3} in an amount of 0.02 to 0.1% by mass. The alumina content is less than 0.005% by mass and
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains MnO ₂ in an amount of 0.03 to 0.06% by mass. The alumina content is 0.005% by mass or more and 2% by mass or less.
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains MnO ₂ in an amount of 0.02 to 0.05% by mass. The alumina content is 0.005% by mass or more and 2% by mass or less.
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains MnO ₂ in an amount of 0.2 to 0.5% by mass. The alumina content is 0.005% by mass or more and 2% by mass or less.
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains Fe ₂ O ₃ in an amount of 0.12 to 0.40% by mass. The alumina content is less than 0.005% by mass and
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains Fe ₂ O ₃ in an amount of 0.12 to 0.23% by mass. The alumina content is 1% by mass or more and 3% by mass or less.
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains 0.3 to 1.0% by mass of CoO. The alumina content is 0.005% by mass or more and 2% by mass or less.
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains Pr ₆ O ₁₁ in an amount of 0.20 to 0.60% by mass. The alumina content is 0.005% by mass or more and 2% by mass or less.
The zirconia powder according to any one of claims 1 to 5, which contains 0.03 to 0.30% by mass of SiO ₂ as the oxide. The alumina content is 1% by mass or more and 3% by mass or less.
As the oxide, CoO is contained in an amount of 0.3 to 1.0% by mass, Cr _{2O 3} is contained in an amount of 0.05 to 0.25% by mass, and MnO ₂ is contained in an amount of 0.03 to 0.2% by mass. The zirconia powder according to any one of claims 1 to 5. The alumina content is 1% by mass or more and 3% by mass or less.
The oxide is characterized by containing 0.2 to 0.8% by mass of CoO, 0.26 to 0.7% by mass of Cr _{2O 3} , and 0.21 to 0.4% by mass of MnO ₂ . The zirconia powder according to any one of claims 1 to 5. The alumina content is 1.5% by mass or more and 4% by mass or less.
As the oxide, Fe ₂ O ₃ is 0.1 to 0.5% by mass, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.3 to 0.9% by mass, and TiO ₂ is 0.2 to 0.2. The zirconia powder according to any one of claims 1 to 5, which contains 0.4% by mass. The alumina content is 0.5% by mass or more and 2.5% by mass or less.
As the oxide, Fe ₂ O ₃ is 0.02 to 1% by mass, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.03 to 0.3% by mass, and TIO ₂ is 0.01 to 0%. The zirconia powder according to any one of claims 1 to 5, which comprises 1% by mass. The alumina content is 1% by mass or more and 3% by mass or less.
The zirconia powder according to any one of claims 1 to 5, wherein the oxide contains 1.05 to 2% by mass of CoO. Step X of molding the zirconia powder according to any one of claims 1 to 12 to obtain a molded body, and
A method for producing a zirconia sintered body, which comprises the step Y of sintering the molded body after the step X. Contains one or more oxides selected from the group consisting of Group 4-9, Group 12, Group 14 and lanthanoid elements.
A zirconia sintered body, which is obtained by the production method according to claim 23. The 4th to 9th groups are one or more selected from the group consisting of Ti, V, Cr, Mn, Fe, and Co.
The 12th group is Zn, and the group 12 is Zn.
The 14th group is Si,
The zirconia sintered body according to claim 24, wherein the lanthanoid element is at least one selected from the group consisting of Er, Tb, and Pr. Fe ₂ O ₃ is 0.4 to 1.0% by mass, CoO is 0.9 to 1.5% by mass, Cr ₂ O ₃ is 1.0 to 1.6% by mass, and TIO ₂ is 0.5 to 0. .9 mass% included
L ^* a ^* b ^* L ^* specified in the color system is -1 or more and 13 or less, a ^* is -7 or more and 7 or less, and b ^* is -8 or more and 6 or less. The zirconia sintered body according to claim 24. It contains 0.9 to 1.5% by mass of CoO, 1.0 to 1.6% by mass of Cr _{2O 3} , and 0.8 to 1.4% by mass of MnO ₂ .
L ^* a ^* b ^* Claims characterized in that L ^* specified in the color system is 1 or more and 17 or less, a ^* is -9 or more and 5 or less, and b ^* is -8 or more and 6 or less. Item 24. The zirconia sintered body according to item 24. Contains 0.15 to 0.35% by mass of ZnO.
L ^* a ^* b ^* Claims characterized in that L ^* specified in the color system is 80 or more and 96 or less, a ^* is -7 or more and 7 or less, and b ^* is -6 or more and 8 or less. Item 24. The zirconia sintered body according to item 24. Contains 0.02 to 0.1% by mass of Cr ₂ O ₃
A claim characterized in that L ^* defined by the L ^* a ^* b ^* color system is 30 or more and 52 or less, a ^* is -5 or more and 8 or less, and b ^* is 0 or more and 20 or less. 24. The zirconia sintered body. The alumina content is less than 0.005% by mass and
Contains 0.03 to 0.06% by mass of MnO ₂
L ^* a ^* b ^* Claims characterized in that L ^* specified in the color system is 28 or more and 44 or less, a ^* is -3 or more and 8 or less, and b ^* is -8 or more and 8 or less. Item 24. The zirconia sintered body according to item 24. The alumina content is 0.005% by mass or more and 2% by mass or less.
Contains 0.02 to 0.05% by mass of MnO ₂
L ^* a ^* b ^* Claims characterized in that L ^* specified in the color system is 31 or more and 47 or less, a ^* is -4 or more and 12 or less, and b ^* is -9 or more and 7 or less. Item 24. The zirconia sintered body according to item 24. The alumina content is 0.005% by mass or more and 2% by mass or less.
Contains 0.2-0.5% by mass of MnO ₂
L ^* a ^* b ^* Claims characterized in that L ^* specified in the color system is 1 or more and 23 or less, a ^* is -5 or more and 11 or less, and b ^* is -10 or more and 6 or less. Item 24. The zirconia sintered body according to item 24. The alumina content is 0.005% by mass or more and 2% by mass or less.
Contains 0.12 to 0.40% by mass of Fe ₂ O ₃
A claim characterized in that L ^* defined by the L ^* a ^* b ^* color system is 55 or more and 75 or less, a ^* is -2 or more and 17 or less, and b ^* is 18 or more and 40 or less. 24. The zirconia sintered body. The alumina content is less than 0.005% by mass and
Contains 0.12 to 0.23% by mass of Fe ₂ O ₃
24. Claim 24, wherein L ^* defined by L ^* a ^* b ^* color system is 41 or more and 61 or less, a ^* is 2 or more and 18 or less, and b ^* is 18 or more and 38 or less. The zirconia sintered body described in. The alumina content is 1% by mass or more and 3% by mass or less.
Contains 0.3-1.0% by mass of CoO
L ^* a ^* b ^* L ^* specified in the color system is 22 or more and 44 or less, a ^* is -10 or more and 7 or less, and b ^* is -50 or more and -28 or less. The zirconia sintered body according to claim 24. The alumina content is 0.005% by mass or more and 2% by mass or less.
Contains 0.20 to 0.60% by mass of Pr ₆ O ₁₁ .
24. Claim 24, wherein L ^* defined by L ^* a ^* b ^* color system is 55 or more and 75 or less, a ^* is 4 or more and 20 or less, and b ^* is 40 or more and 60 or less. The zirconia sintered body described in. The alumina content is 0.005% by mass or more and 2% by mass or less.
Containing 0.03 to 0.30% by mass of SiO ₂
L ^* a ^* b ^* Claims characterized in that L ^* specified in the color system is 77 or more and 97 or less, a ^* is -5 or more and 5 or less, and b ^* is -5 or more and 5 or less. Item 24. The zirconia sintered body according to item 24. The alumina content is 1% by mass or more and 3% by mass or less.
CoO is contained in an amount of 0.3 to 1.0% by mass, Cr _{2O 3} is contained in an amount of 0.05 to 0.25% by mass, and MnO ₂ is contained in an amount of 0.03 to 0.2% by mass.
L ^* a ^* b ^* L ^* specified in the color system is 13 or more and 33 or less, a ^* is -12 or more and -2 or less, and b ^* is -29 or more and -19 or less. The zirconia sintered body according to claim 24. The alumina content is 1% by mass or more and 3% by mass or less.
It contains 0.2 to 0.8% by mass of CoO, 0.26 to 0.7% by mass of Cr _{2O 3} , and 0.21 to 0.4% by mass of MnO ₂ .
L ^* a ^* b ^* L ^* specified in the color system is 8 or more and 28 or less, a ^* is -14 or more and -4 or less, and b ^* is -21 or more and -11 or less. The zirconia sintered body according to claim 24. The alumina content is 1.5% by mass or more and 4% by mass or less.
Fe ₂ O ₃ is 0.1 to 0.5% by mass, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.3 to 0.9% by mass, and TIO ₂ is 0.2 to 0.4% by mass. Including,
L ^* a ^* b ^* L ^* specified in the color system is 27 or more and 48 or less, a ^* is -6 or more and 4 or less, and b ^* is -10 or more and -1 or less. The zirconia sintered body according to claim 24. The alumina content is 0.5% by mass or more and 2.5% by mass or less.
Fe ₂ O ₃ is 0.02 to 1% by mass, CoO is 1 to 2% by mass, Cr ₂ O ₃ is 0.03 to 0.3% by mass, and TiO ₂ is 0.01 to 0.1% by mass.
L ^* a ^* b ^* L ^* specified in the color system is 27 or more and 48 or less, a ^* is -6 or more and 4 or less, and b ^* is -10 or more and -1 or less. The zirconia sintered body according to claim 24. The alumina content is 1% by mass or more and 3% by mass or less.
Contains 1.05 to 2% by mass of CoO
L ^* a ^* b ^* L ^* specified in the color system is 27 or more and 48 or less, a ^* is -5 or more and 6 or less, and b ^* is -12 or more and -2 or less. The zirconia sintered body according to claim 24.