JP7120340B2 - Zirconia sintered body and its use - Google Patents

Description

TECHNICAL FIELD The present invention relates to a zirconia sintered body in which zirconias having different color tones are bonded by sintering. More specifically, it relates to a zirconia sintered body in which zirconias having different color tones are bonded by sintering, one zirconia forming a pattern on the other zirconia.

Since the zirconia sintered body has high toughness, high strength, and gloss, it can be used as a member exhibiting a high-grade appearance. Therefore, zirconia sintered bodies are used as various members such as luxury watch parts and ornaments. The color tone of the zirconia sintered body is monochromatic in spite of being a member exhibiting a high-class appearance. Moreover, different shades of zirconia usually have different sintering behavior. Therefore, when zirconias with different color tones are sintered at the same time, cracks, fissures, distortions, etc. occur, and it is not possible to obtain defect-free zirconia sintered bodies. Therefore, it was not possible to obtain a zirconia sintered body having two or more different color tones and a member made of this.

In order to make a member having two or more different color tones using a zirconia sintered body, a zirconia sintered body is combined with a material other than the zirconia sintered body that has a color tone different from that of the zirconia sintered body. A member with the same thickness is being studied (for example, Patent Documents 1 and 2). However, these members differ greatly in texture between materials. As a result, the resulting member exhibits a design that is different from that of a member made of only ceramics, and in particular, it spoils the high-class feeling peculiar to the zirconia sintered body.

Also, a ceramic joined body in which two or more ceramics are joined via an intermediate layer such as an adhesive is conventionally known. However, the ceramic bonded body is prone to breakage originating from the intermediate layer. Therefore, in a zirconia sintered body characterized by high toughness and high strength, it is not preferable to use an intermediate layer as a bonded body.

On the other hand, Patent Document 3 reports a zirconia sintered body obtained by sintering two zirconia molded bodies having different color tones. Patent Document 3 discloses a zirconia sintered body obtained by sintering a zirconia powder compact containing FeCrNi spinel and a zirconia powder compact containing CoAl.

JP 2011-191321 A Patent No. 4370361 JP-A-08-081255

The sintered body disclosed in Patent Document 3 consists of a zirconia sintered body. There is no difference in texture between members. However, the sintered bodies have a visible "color transition zone" between zirconia sintered bodies having different shades. Such color transition bands are viewed as "color bleeding". Boundaries between zirconia sintered bodies become unclear due to color bleeding. As a result, the portion where the zirconia sintered bodies are in contact with each other, especially the pattern formed by one of the zirconia sintered bodies, becomes unclear. Such an unclear pattern gives the impression that the zirconia sintered body further impairs its high-class appearance.

Patent Document 3 also discloses a zirconia sintered body that does not have a color transition zone. However, the zirconia sintered body had a gap at the boundary between the zirconia sintered bodies because sintering had not progressed sufficiently. In the zirconia sintered body having no color transition zone in Patent Document 3, the color simply did not shift due to the gaps. The gap is visually recognized as a color tone different from that of any zirconia sintered body, and deteriorates the aesthetic appearance of the member. In addition to this, a gap existing at the boundary between zirconia sintered bodies becomes a starting point of fracture. Therefore, such a zirconia sintered body has remarkably low mechanical strength and is fragile as a member.

Furthermore, in the sintered body disclosed in Patent Document 3, it is necessary to enlarge the pattern to such an extent that color bleeding and gaps do not affect the aesthetics of the member. Therefore, the sintered body disclosed in Patent Document 3 cannot be a sintered body having a fine pattern.

The present invention solves these problems, and provides a zirconia sintered body having two or more different color tones, which has an aesthetic appearance that gives a high-class impression, and a zirconia that has sufficient strength to be used as a member. An object is to provide a sintered body. In particular, the present invention relates to a multicolor zirconia sintered body comprising a zirconia sintered body exhibiting pink, orange, lavender and other colors and a zirconia sintered body exhibiting other color tones, and is aesthetically pleasing to the eye. It is another object of the present invention to provide a zirconia sintered body having sufficient strength to be used as a member.

The present inventors have proposed a zirconia sintered body having two or more different color tones, particularly a zirconia sintered body having two or more different color tones, wherein one zirconia is formed as a pattern on the surface of the other zirconia. A zirconia sintered body was investigated.

As a result, the inventors have found that zirconia sintered bodies having two or more different color tones can be obtained by simultaneously sintering a zirconia molded body in which at least one of the molded bodies contains a lanthanide and another zirconia molded body. Furthermore, in such a zirconia sintered body, the zirconia sintered body and the zirconia sintered body form a grain boundary as a joint surface, and the interface does not have color bleeding or gaps. The present invention has been completed.

That is, the gist of the present invention is as follows.
[1] A zirconia sintered body including a first zirconia sintered body and a second zirconia sintered body, wherein the first zirconia sintered body contains Ce, Pr, Nd, Eu, Tb, Ho, Er, A zirconia sintered body containing at least one lanthanoid selected from the group consisting of Yb and Gd, the second zirconia sintered body containing at least aluminum oxide, and the first zirconia sintered body A zirconia sintered body, wherein the zirconia sintered body and the second zirconia sintered body form grain boundaries, and the grain boundaries do not have gaps or color bleeding.
[2] The zirconia sintered body of either the first zirconia sintered body or the second zirconia sintered body forms a pattern on the surface of the other zirconia sintered body. A zirconia sintered body as described.
[3] The zirconia sintered body according to any one of [1] and [2], which has a relative density of 99.5% or more.
[4] The zirconia sintered body according to any one of claims 1 to 3, wherein the lanthanoid contained in the first zirconia sintered body is at least one selected from the group consisting of Ce, Pr, Nd and Er. body.
[5] The zirconia sintered body according to any one of [1] to [4], wherein the first zirconia sintered body has a lanthanoid content of 0.1% by weight or more and 6% by weight or less.
[6] The zirconia sintered body according to any one of [1] to [5], wherein the first zirconia sintered body contains alumina.
[7] The zirconia sintered body according to Claim 6, wherein the first zirconia sintered body contains 1% by weight or less of alumina relative to the zirconia in the first zirconia sintered body.
[8] The zirconia sintered body according to any one of claims 1 to 7, wherein the second zirconia sintered body contains 0.25% by weight or more and 20% by weight or less of aluminum oxide. .
[9] A member containing the zirconia sintered body according to any one of [1] to [8].

According to the present invention, there is provided a zirconia sintered body having two or more different color tones, having an aesthetic appearance that gives a high-class impression, and having sufficient strength to be used as a member. can. Further, according to the present invention, it is possible to provide zirconia sintered bodies having two or more different color tones without color bleeding or gaps between the zirconia sintered bodies. Furthermore, according to the present invention, it is possible to provide a member having a high-class appearance.

Backscattered electron image of the pink/white zirconia sintered body of Example 1 (the scale in the figure is 50 μm) Backscattered electron image of multicolored zirconia sintered body with interstices (scale in the figure is 50 μm) Optical micrograph of multicolored zirconia sintered body with color bleeding (scale in the figure is 50 μm) Schematic diagram showing the measurement of the transition region by quantitative point analysis of EPMA Backscattered electron image of the orange/white zirconia sintered body of Example 2 (the scale in the figure is 50 μm) Schematic diagram showing an example of a watch bezel ring made of the multicolor zirconia sintered body of the present invention. Schematic diagram showing an example of a watch dial made of the multicolor zirconia sintered body of the present invention. Schematic diagram showing an example of a bracelet made of the multicolor zirconia sintered body of the present invention. Schematic diagram showing an example of a housing made of the multicolor zirconia sintered body of the present invention. Schematic diagram showing an example of a mobile phone cover made of the multicolored zirconia sintered body of the present invention. Schematic diagram showing an example of a disk-shaped sintered body made of the multicolored zirconia sintered body of the present invention. Appearance photographs of the red/white zirconia sintered body of Example 4 (a: photograph from directly above, b: photograph from right side) (a) Optical microscope photograph and (b) SEM photograph of the interface of the ceramic shaped article of Comparative Example 1 (the scale in the figure is 20 μm) SEM photograph of the interface of the ceramic shaped article of Comparative Example 2 (the scale in the figure is 20 μm) (a) Appearance photograph and (b) enlarged view of the ceramic shaped article of Comparative Example 3 Optical micrograph of the interface having gaps in the ceramic shaped article of Comparative Example 3 Optical micrograph of the interface with color bleeding of the ceramic shaped article of Comparative Example 3

The zirconia sintered body of the present invention will be described below.

The zirconia sintered body of the present invention is a zirconia sintered body including a first zirconia sintered body and a second zirconia sintered body (hereinafter also referred to as "multicolor zirconia sintered body"). The first zirconia sintered body (hereinafter also referred to as "light-colored sintered body") and the second zirconia sintered body (hereinafter also referred to as "light-colored sintered body") are zirconia having different color tones. It is a sintered body. The multicolored zirconia sintered body of the present invention includes a light-colored sintered body containing a lanthanide as a coloring material and a light-colored sintered body, preferably substantially composed of the light-colored sintered body and the light-colored sintered body. As a result, it is possible to obtain a member that consists only of a zirconia sintered body and that has an aesthetic appearance that gives a high-class impression.

In the multicolor zirconia sintered body of the present invention, the light-colored sintered body and the light-colored sintered body form grain boundaries. Both sintered bodies are thereby joined together. Furthermore, the light-colored sintered body and the light-colored sintered body have grain boundaries (hereinafter also referred to as "interfaces") formed by sintering. By sintering the interface, the interface becomes a bonding surface without defects such as cracks and strains. This prevents the interface from becoming the starting point of destruction. Therefore, the multicolored zirconia sintered body of the present invention can also be used as a member for which the original strength of the zirconia sintered body is required.

By sintering the light-colored sintered body and the light-colored sintered body, they become one continuous zirconia sintered body. Therefore, the multicolor zirconia sintered body of the present invention has a structure in which crystal grains of the light-colored sintered body are sintered together, and a structure in which crystal grains of the light-colored sintered body are sintered together. and the crystal grains of the light-colored sintered body are sintered.

Therefore, the multicolored zirconia sintered body of the present invention is different from a zirconia composite or a zirconia bonded body that does not have such a grain structure. A zirconia composite or a zirconia bonded body consists only of a structure in which crystal grains of a light-colored sintered body are sintered together, and a structure in which crystal grains of a light-colored sintered body are sintered together. As a zirconia composite, for example, a zirconia composite obtained by separately sintering a light-colored sintered body and a light-colored sintered body and then combining them can be mentioned. Examples of the zirconia bonded body include a zirconia bonded body in which a light-colored sintered body and a light-colored sintered body are integrated via an adhesive layer or other intermediate layer. Furthermore, even when a zirconia composite or a zirconia bonded body is HIP-treated, it does not include a grain structure having a grain structure in which grains of a dark-colored sintered body are sintered. In the HIP treatment, open pores included in each of the light-colored sintered body and the dark-colored sintered body are eliminated, and the densification of each sintered body proceeds only. This is because it is impossible to sinter between Thus, the HIP treatment of the zirconia composite only strengthens the physical fitting due to the shrinkage of the individual sintered bodies.

The interface in the present invention can be confirmed from an electron image obtained by observation with an electron microscope such as a scanning electron microscope (hereinafter referred to as "SEM") or observation with an optical microscope. The light-colored sintered body and the light-colored sintered body have different color tones. Therefore, in observation with an optical microscope, the interface can be confirmed by the portion where the color tone changes. Moreover, the light-colored sintered body and the light-colored sintered body differ at least in coloring components. Since the electronic image presents different color tones due to the difference in the coloring components, the interface can be confirmed by the portion where the color tone changes in the electronic image.

FIG. 1 is a diagram showing an example of a backscattered electron image obtained by SEM observation of the multicolored zirconia sintered body of the present invention. In FIG. 1, the area (1) is the light-colored sintered body, and the area (2) is the light-colored sintered body. From FIG. 1, the interface (3), which is the boundary between the regions (1) and (2), can be confirmed from the difference in color tone in the backscattered electron image (for example, the dashed circle in FIG. 1).

In the multicolor zirconia sintered body of the present invention, the light-colored sintered body and the light-colored sintered body are bonded by sintering. Furthermore, one of the light-colored sintered body and the light-colored zirconia sintered body has a concave portion, and the other zirconia sintered body has a convex portion, and the concave portion and the convex portion are combined. As shown, it is preferable that the light-colored sintered body and the light-colored sintered body are laminated and joined. By combining such zirconia sintered bodies, a pattern without steps and gaps can be formed on the surface of the multicolor zirconia sintered body of the present invention.

In the multicolor zirconia sintered body of the present invention, the light-colored sintered body and the light-colored sintered body have an interface in this way, and the interface does not have a gap. As a result, the multicolored zirconia sintered body of the present invention can exhibit aesthetics created only from the zirconia sintered body, and the multicolored zirconia sintered body of the present invention can be used as a member that gives a more luxurious impression. can. In addition, since there is no gap at the interface, fracture originating from the interface is less likely to occur, so that the original mechanical properties of the zirconia sintered body are not impaired.

In the present invention, the gap is the interface between the light-colored sintered body and the light-colored sintered body and the gap formed in the vicinity thereof, which is obtained by optical microscope observation or SEM observation at a magnification of 500 times or less. It can be confirmed by an electron image of at least one of a secondary electron image and a backscattered electron image (hereinafter collectively referred to simply as an "electron image").

The multicolor zirconia sintered body of the present invention preferably does not contain fine voids such as voids that can be confirmed by secondary electron images or backscattered electron images obtained by SEM observation at a magnification of more than 500 times. However, when the multicolor zirconia sintered body of the present invention is used as various members, in the electron image obtained by SEM observation at a magnification of more than 500 times or transmission electron microscope (hereinafter referred to as "TEM") observation, It may have a gap that is Such fine voids do not substantially affect the aesthetic appearance of the visible member.

In FIG. 1, the interface (3), which is the boundary between the regions (1) and (2), can be confirmed from the difference in color tone in the backscattered electron image (for example, the dashed circle in FIG. 1). Furthermore, the interface confirmed in FIG. 1 is a continuous interface, and voids are not confirmed in the interface. On the other hand, FIG. 2 is a diagram showing a backscattered electron image obtained by observing a multicolor zirconia sintered body having interstices at the interface with an SEM at a magnification of 500 times. In FIG. 2, (4) is a zirconia sintered body containing no coloring agent, and (5) is a zirconia sintered body containing a coloring agent (hereinafter also referred to as "colored zirconia sintered body"). The interface between the two is not a continuously formed interface but a partially formed interface (broken circle in FIG. 2). Furthermore, it can be confirmed that a part of the interface is peeled off and a gap is formed (indicated by an arrow in FIG. 2).

The multicolor zirconia sintered body of the present invention has an interface between a light-colored sintered body and a light-colored sintered body, and does not have color bleeding at the interface. As a result, the boundary between the light-colored sintered body and the light-colored sintered body becomes clear, so that the multicolored zirconia sintered body of the present invention can be used as a member having a clear pattern. Furthermore, the pattern formed by one zirconia sintered body can be a fine pattern.

Color fringing is a portion exhibiting a color tone in which the color tone of the light-colored sintered body and the color tone of the light-colored sintered body are mixed, and is observed visually or with an optical microscope. Furthermore, the color bleeding at the interface includes the color tone of the interface and the vicinity of the interface ( hereinafter also referred to as “transition region”), which is observed visually or with an optical microscope. In the present invention, the term "color bleeding at the interface" refers to the interface including the color tone of the light-colored sintered body or the light-colored sintered body, which is observed in at least one of the light-colored sintered bodies, and the region near the interface. , which is specifically meant to be observed visually or with an optical microscope. The presence or absence of color bleeding at the interface can be confirmed visually or by observing the multicolored zirconia sintered body with an optical microscope at a magnification of 10 to 100 times.

FIG. 3 is an optical microscope photograph showing an example of a multicolor zirconia sintered body having color bleeding. In FIG. 3, the region (4) is a zirconia sintered body containing no colorant, and the region (5) is a colored zirconia sintered body. From FIG. 3, the boundary between the regions (4) and (5) is blurred and the vicinity of the interface is unclear (for example, the dashed square in FIG. 3). It can be confirmed that such a multicolor zirconia sintered body has color bleeding near the interface.

The multicolored zirconia sintered body of the present invention may have transition regions that cannot be observed visually or with an optical microscope. The transitional region, which cannot be observed visually or with an optical microscope, does not substantially affect aesthetics when the multicolored zirconia sintered body of the present invention is used as various members.

As a transition region that cannot be observed with the naked eye or an optical microscope, the region of either the light-colored sintered body or the light-colored zirconia sintered body, the other containing the coloring component contained in the one zirconia sintered body zirconia sintered body region.

If the coloring component contained in the transition region is 3% by weight or less, further 2.5% by weight or less, or further 2% by weight or less, color bleeding does not occur. Here, the presence or absence of the transition region and the content of the attached components are all obtained by quantitative point analysis (hereinafter referred to as "EPMA analysis") of the colored sintered body at a certain distance from the interface with an electron probe microanalyzer. It is the presence or absence and weight ratio of the coloring component with respect to the weight of the element.

FIG. 4 is a schematic diagram showing measurement of the transition region by EPMA analysis. In FIG. 4, (1) is the region of the light-colored sintered body, (2) is the region of the light-colored sintered body, and (3) is the interface. Furthermore, (6) is a region of the light-colored sintered body at a certain distance from the interface, and (7) is a circle with a diameter of 10 μm centered on the region (6). In the EPMA analysis, all the elements contained in (7) are analyzed, and if a coloring component is contained, the region becomes a transition region. In the present invention, EPMA analysis is performed on a plurality of regions with different distances from the interface (regions corresponding to (6) in FIG. 4), and the region containing the colored component corresponding to the maximum distance from the interface is determined in the sample. It was set as the transition region of each coloring component.

The transition region is a region corresponding to the maximum distance from the interface containing the coloring component, and includes a region within 200 μm from the interface, a region within 150 μm, and a region within 100 μm. The area of the other sintered body within 200 μm, the area of the other sintered body within 150 μm, or the area of the other sintered body within 100 μm can be mentioned.

If the transition region has the region and the amount of the coloring agent within the above ranges, there is no color blurring that affects aesthetics when the multicolor zirconia sintered body of the present invention is used as a member.

The coloring component contained in the transition region can include lanthanoid elements, and at least one of the group consisting of Ce, Pr, Nd, Eu, Tb, Ho, Er, Yb and Gd.

For example, the light-colored sintered body contained in the multicolored zirconia sintered body of the present invention has a transition region within 100 μm from the interface, and the same type of lanthanoid as the lanthanide contained in the light-colored sintered body is contained in the region. 1% by weight or less, further 0.6% by weight or less, or further 0.3% by weight or less, but the same kind as the lanthanide contained in the light-colored sintered body in the region of the light-colored sintered body beyond the transition region lanthanoid-free. In this case, the lanthanide migration region is within 100 μm from the interface.

In the multicolor zirconia sintered body of the present invention, it is preferable that one of the light-colored sintered body and the light-colored zirconia sintered body forms a pattern on the surface of the other zirconia sintered body. . The pattern is formed by exposing the interface between the light-colored sintered body and the light-colored sintered body and the light-colored sintered body and the light-colored sintered body on the same surface. The multicolor zirconia sintered body of the present invention can form finer patterns than conventional ones. As a result, it is possible to provide a multicolored zirconia sintered body that not only has a higher designability but also serves as a member that is used in a wider range of applications.

In the present invention, the pattern refers to a diagram, figure, or a combination thereof formed on a part of one of the zirconia sintered bodies of either the light-colored sintered body or the light-colored sintered body of the other zirconia sintered body. is. Specific diagrams include linear lines such as solid lines, dashed lines, and wavy lines, numbers and characters, and geometric shapes such as circles and polyhedrons as figures.

In the multicolor zirconia sintered body of the present invention, it is sufficient that the interface between the light-colored sintered body and the light-colored sintered body, and the light-colored sintered body and the light-colored sintered body are exposed on the same surface to form a pattern. Alternatively, the light-colored sintered body may form a pattern on the surface of the light-colored sintered body, or the light-colored sintered body may form a pattern on the surface of the light-colored sintered body.

The multicolored zirconia sintered body of the present invention can form a pattern of a size that has been obtained with a conventional multicolored zirconia sintered body. In addition to this, the multicolored zirconia sintered body of the present invention can form a clear pattern even in a finer range than conventional ones. The pattern may be, for example, an area of 1 cm ² or less, or even an area of 1 mm ² or less, or an area of 0.5 mm ² or less, or an area of 0.05 mm ² or less, or even an area of 0.005 mm ² or less. If it is a region, it can be clearly formed. Furthermore, the pattern of the multicolored zirconia sintered body of the present invention may be, for example, a diagram consisting of lines with a thickness of about 150 μm, a diagram or figure with an interval of about 150 μm, a diameter of 1 mm or less, and further a diameter of 0.5 mm. A figure of 5 mm or less can be mentioned.

The multicolor zirconia sintered body of the present invention and the pattern shape thereof are arbitrary, but examples of the shape and pattern of the multicolor zirconia sintered body of the present invention are shown in FIGS. 6 to 11 .

For example, FIG. 6 is a schematic diagram of a multicolor zirconia sintered body having the shape of a watch bezel ring and forming the surface of the bezel ring. The left figure is a front view, the middle figure is a side view, and the right figure is a rear view. In the front view, the surface of the bezel ring is made of a light-colored sintered body ((2) in the left figure of FIG. 6), and on the surface is a pattern of Arabic numerals made of a light-colored sintered body ((1) in the left figure of FIG. 6). )). The side view shows that the multicolor zirconia sintered body has a light-colored sintered body having concave portions having the same shape as the Arabic numerals, and a light-colored sintered body having concave portions having the same shape as the Arabic numerals. is shown (figure in FIG. 6). Further, the light-colored sintered body has a ring-shaped shape having a hollow portion, and the light-colored sintered body and the light-colored sintered body are laminated (the right figure in FIG. 6).

Further, for example, FIG. 7 is a schematic diagram of a multicolor zirconia sintered body having the shape of a watch dial. The left figure is a front view, and the right figure is a rear view. In FIG. 7, the sintered body has a disk-like shape, and the surface is made of a light-colored sintered body. On the surface of the sintered body, a diagram of a portion corresponding to each time from 1 o'clock to 12 o'clock of an analog clock, and a pattern of Arabic numerals 3, 6, 9 and 12. It shows that it has cohesion. Also, the light-colored sintered body is disk-shaped, and the light-colored sintered body and the light-colored sintered body are laminated (the right figure in FIG. 7).

8 to 11 are schematic diagrams showing multicolor zirconia sintered bodies having a bracelet shape, a housing shape, a mobile phone cover shape, and a disk shape, respectively.

As illustrated in FIGS. 6 to 11, the multicolor zirconia sintered body of the present invention is a zirconia sintered body including a light-colored sintered body and a light-colored sintered body. The zirconia sintered to have a pattern by sintering so that the uneven part with the body is laminated to form an interface, and the cross section of the part where the uneven part is laminated is exposed on the same surface. can be a body.

Furthermore, by making the uneven portions of the light-colored sintered body and the light-colored sintered body arbitrary shapes and sizes, patterns of arbitrary shapes and sizes can be expressed.

Since the light-colored sintered body and the light-colored sintered body are joined by sintering, the multicolored zirconia sintered body of the present invention has a high density. The multicolor zirconia sintered body of the present invention has a relative density of 99.5% or more, more preferably 99.7% or more. When the relative density is 99.5% or more, not only is there no gap at the interface, but also defects at portions other than the interface are reduced. Thereby, the mechanical strength of the multicolored zirconia sintered body of the present invention tends to be higher.

A zirconia composite and a zirconia bonded body are obtained by combining different zirconia sintered bodies after sintering. Therefore, even if the relative densities of the zirconia sintered bodies forming these are 99.5% or more, the relative densities of the zirconia composite body and the zirconia bonded body are not 99.5% or more.

In the present invention, the relative density of the multicolor zirconia sintered body can be obtained from the following formula (1).
Relative density (%) = Measured density of multicolored zirconia sintered body (g/cm ³ )/Theoretical density of multicolored zirconia sintered body (g/cm ³ ) x 100 (1)

The measured density (sintered body density) of the multicolor zirconia sintered body can be determined by the Archimedes method.

Furthermore, the theoretical density of the multicolored zirconia sintered body can be calculated from the following formula from the respective densities and volume ratios of the light-colored sintered body and the light-colored sintered body.

M = (Ma · X + Mb · Y) / (X + Y) (1')
In the above formula, M is the theoretical density of the multicolored zirconia sintered body (g/cm ³ ), Ma is the theoretical density of the light colored sintered body (g/cm ³ ), Mb is the theoretical density of the light colored sintered body (g /cm ³ ), X is the volume ratio of the light-colored sintered body to the volume of the multi-colored zirconia sintered body, and Y is the volume ratio of the light-colored sintered body to the volume of the multi-colored zirconia sintered body.

In formula (1′), Ma and Mb differ depending on the composition of the light-colored sintered body and the light-colored sintered body. Ma and Mb can be obtained from the theoretical density of the compounds constituting each sintered body and the weight ratio of these compounds. Also, lanthanoid elements form a solid solution in zirconia as a stabilizer, but for calculation purposes, the theoretical density of lanthanoid oxides may be used. Examples of theoretical densities of compounds constituting each sintered body include the following.
Zirconia containing 3 mol% yttria: 6.09 g/cm ³
Praseodymium oxide: 7.07 g/ ^cm3
Neodymium oxide: 7.24 g/ ^cm3
Erbium oxide: 8.64 g/ ^cm3
Cerium oxide: 7.22 g/ ^cm3
Aluminum oxide: 3.98 g/ ^cm3

In the formula (1′), X is the volume ratio obtained by multiplying the weight ratio of the light-colored sintered body to the weight of the multi-colored zirconia sintered body by Ma, and Y is the light-colored to the weight of the multi-colored zirconia sintered body. It is a volume ratio obtained by multiplying the weight ratio of the sintered body by Mb.

The light-colored sintered body and the light-colored sintered body are 2 mol% or more and 6 mol% or less, further 2.5 mol% or more and 4 mol% or less, further 2.5 mol% or more and 3.5 mol% or less, or further 2.8 mol% % or more and 3.2 mol % or less of the stabilizer. By containing the stabilizer within the above range, these zirconia sintered bodies become zirconia sintered bodies having a tetragonal crystal structure. As a result, a sintered body having high mechanical strength is obtained.

Stabilizers include at least one selected from the group consisting of yttria, calcia, magnesia, scandia and lanthanides, and yttria.

The light-colored sintered body contained in the multicolored zirconia sintered body of the present invention is any one or more lanthanoids selected from the group consisting of Ce, Pr, Nd, Eu, Tb, Ho, Er, Yb and Gd (hereinafter referred to as " It is a zirconia sintered body containing a colored lanthanide. As a result, the sintered body becomes a zirconia sintered body having a light color tone.

The coloration of the light-colored sintered body may be any desired color tone. For example, L ^* in the L ^* a ^* b ^* color system is 55 or more.

In the present invention, the colored lanthanoid is at least one lanthanoid selected from the group consisting of Ce, Pr, Nd, Eu, Tb, Ho, Er, Yb and Gd, and selected from the group consisting of Er, Pr, Ce and Nd. Any one or more lanthanoids are preferred. For example, a pink zirconia sintered body containing erbium (Er), an orange zirconia sintered body containing praseodymium (Pr), a red zirconia sintered body containing cerium (Ce), and , a lavender-colored zirconia sintered body is obtained by containing neodymium (Nd).

The content of the colored lanthanoid should be an amount that dissolves in the zirconia of the light-colored sintered body, and further, the colored lanthanoid is 0.1% by weight or more and 6% by weight based on the weight of the light-colored sintered body. 0.3% by weight or more and 3.5% by weight or less, preferably 0.5% by weight or more and 2.5% by weight or less.

The light-colored sintered body may contain alumina in addition to the colored lanthanide. In this case, the alumina contained in the light-colored sintered body is 1% by weight or less, further 0.5% by weight or less, further 0.3% by weight or less, or even 0% by weight with respect to the zirconia of the light-colored sintered body. .25% by weight or less and less than the alumina content of the light-colored sintered body. If the alumina content exceeds 1% by weight, the coloration becomes too light.

Since the light-colored sintered body preferably exhibits a light color tone, it is preferable that the coloring agent is substantially only a colored lanthanide, and that it does not contain a complex oxide having a spinel structure.

When the light-colored sintered body exhibits a pink color, the coloration should be L ^* =65 or more and 85 or less, a ^* =0 or more and 15 or less, and b ^* =-10 or more and 0 or less, and further L ^* = 70 or more and 85 or less, a ^* = 2 or more and 12 or less, and b* = -8 or more and -0.5 or less.

When the light-colored sintered body exhibits an orange color, the coloration should be L ^* = 55 or more and 80 or less, a ^* = 0 or more and 20 or less, and b ^* = 30 or more and 65 or less, and further L ^* = 60. It is preferable that a ^* =3 or more and 18 or less, and b ^* =35 or more and 65 or less.

When the light-colored sintered body exhibits a lavender color, the coloration should be L ^* = 55 or more and 80 or less, a ^* = 3 or more and 15 or less, and b ^* = -15 or more and -3 or less ^. = 60 or more and 80 or less, a ^* = 5 or more and 15 or less, and b ^* = -11 or more and -5 or less.

When the light-colored sintered body exhibits a red color, the coloration should be L ^* = 20 or more and 60 or less, a ^* = 30 or more and 60 or less, and b ^* = 25 or more and 60 or less, and further L ^* = 20 or more. 60 or less, a ^* = 35 or more and 60 or less, and b ^* = 30 or more and 60 or less.

The light-colored sintered body contained in the multicolored zirconia sintered body of the present invention is a zirconia sintered body containing at least aluminum oxide (alumina). As a result, the sintered body becomes a zirconia sintered body having a whitish color tone.

The coloration of the light-colored sintered body may be any desired color tone, for example, L ^* of 55 or more in the L ^* a ^* b ^* color system.

The light-colored sintered body contains aluminum oxide (alumina). By containing alumina, the alumina particles are dispersed among the zirconia crystal particles. As a result, the inherent transparency of zirconia is suppressed, resulting in a zirconia sintered body exhibiting a clear white color. Furthermore, since the light-colored sintered body contains only the stabilizer and alumina, the formation of interfaces free of gaps and color bleeding is facilitated during sintering.

The content of alumina is 0.25% by weight or more and 20% by weight or less, further 1% by weight or more and 15% by weight or less, or further 5% by weight or more and 10% by weight or less as the weight of alumina relative to the weight of the light-colored sintered body. Preferably. By containing alumina in this range, the color tone of the light-colored sintered body becomes more vivid white. Further, when the content of alumina is within the above range, the sintering of zirconia proceeds without being hindered by the alumina particles. When the light-colored sintered body contains alumina in the multi-colored zirconia sintered body, the alumina content of the light-colored sintered body is within the above range and should be higher than the alumina content of the light-colored sintered body.

The coloration of the light-colored sintered body is represented by L ^* , a ^* , and b ^* in the L ^* a ^* b ^* color system (hereinafter also simply referred to as "L ^* ,""a ^* ," and "b ^* ," respectively). ) is L ^* = 85 or more and 100 or less, a ^* = -2 or more and 2 or less, and b ^* = -2 or more and 3.0 or less, and L ^* = 85 or more and 95 or less, a ^* = - 1 or more and -0.5 or less, and b ^* = 0 or more and 1.5 or less, or L ^* = 85 or more and 93 or less, a ^* = -1 or more and -0.4 or less, and b ^* = 0.5 or more and 1.3 or less. When the lightness L ^* is 85 or more and both a ^* and b ^* are near zero, the sintered body exhibits a clear pure white color. By combining this with the light-colored sintered body, it is possible to obtain a member with higher aesthetics.

The light-colored sintered body preferably contains only alumina, but may contain a coloring agent other than alumina as long as the sintered body exhibits a color tone different from that of the light-colored sintered body. Examples of the coloring agent contained in the light-colored sintered body include colored lanthanoids of a different kind from those contained in the light-colored sintered body. Since the light-colored sintered body preferably exhibits a lighter color tone than the light-colored sintered body, it preferably does not contain a composite oxide having a spinel structure.

Next, the method for producing the multicolored zirconia sintered body of the present invention will be described.

The multicolor zirconia sintered body of the present invention is a zirconia powder containing at least one lanthanoid selected from the group consisting of Ce, Pr, Nd, Eu, Tb, Ho, Er, Yb and Gd, or at least A primary molding step of molding one of the zirconia powders containing aluminum oxide to obtain a primary molded body, and molding the other zirconia powder on the primary molded body at a molding temperature equal to or lower than the primary molding step to form a secondary molding. A secondary molding step of obtaining a molded body, a sintering step of firing the secondary molded body at 1300° C. or higher to obtain a pre-sintered body, and sintering the pre-sintered body at 1250° C. or higher and 1650° C. or lower and 100 MPa or higher and 250 MPa or lower. It can be manufactured by a manufacturing method including a hot isostatic pressing step in which hot isostatic pressing is performed at .

In the primary molding step, a primary molded body is obtained. The primary compact is a zirconia powder containing at least one lanthanoid (colored lanthanoid) selected from the group consisting of Ce, Pr, Nd, Eu, Tb, Ho, Er, Yb and Gd (hereinafter referred to as "light-colored powder ”) (hereinafter also referred to as “light-colored molded body”), or a molded body obtained by molding zirconia powder containing at least aluminum oxide (hereinafter also referred to as “light-colored powder”). (Hereinafter, also referred to as "light-colored molded article").

Any molding method may be used in the primary molding step. The molding method may include any one or more molding methods from the group of press molding, cold isostatic pressing, casting, sheet molding and injection molding. The molding method is preferably at least one of cast molding and injection molding, since a molded article having an arbitrary shape can be easily obtained. Further, the molding method is more preferably injection molding because it is easy to obtain a molded article having a more complicated and fine shape. It is preferable that the primary molded body has a shape having uneven portions. Since the primary molded body has a shape having uneven portions, a secondary molded body having a structure in which the light-colored molded body and the light-colored molded body cover the uneven portions with each other can be obtained.

In the secondary molding step, a molded body is produced by molding the powder of the other light-colored molded body or light-colored molded body on top of the primary molded body. As a result, a molded body in which the primary molded body and the secondary molded body are laminated, particularly a secondary molded body in which the light-colored molded body and the light-colored molded body are laminated so as to cover each other's uneven portions are obtained.

The molding temperature in the secondary molding process (hereinafter also referred to as "secondary molding temperature") is set to be equal to or lower than the molding temperature in the primary molding process (hereinafter also referred to as "primary molding temperature"). When the secondary molding temperature is higher than the primary molding temperature, the shape of the primary molded body tends to be distorted or collapsed during secondary molding. In this case, a secondary molded body is obtained that includes the fine shapes of the primary molded body such as convex portions in a distorted state. When such a secondary molded body is sintered, the obtained multicolor zirconia sintered body becomes a sintered body having color bleeding due to shape distortion.

In general molding methods including primary molding and secondary molding, particularly casting molding and injection molding including primary molding and secondary molding, the temperature of the primary molded body rises due to heat during secondary molding. This increases the temperature of the secondary molding process. Therefore, when the molding temperature is not controlled in primary molding and secondary molding, the secondary molding temperature usually exceeds the primary molding temperature. On the other hand, the secondary molding temperature in the present invention is below the primary molding temperature, further below the primary molding temperature. When the secondary molding temperature is equal to or lower than the primary molding temperature, that is, the primary molding temperature is equal to or higher than the secondary molding temperature, pattern flow and color bleeding due to this do not occur. By sintering the thus-obtained secondary compact, a multicolored zirconia sintered body having no interstices and no color bleeding can be obtained. The flow of the pattern includes deformation of the shape of the primary molded body, such as a convex portion of the primary molded body, due to molding of the secondary molded body.

In the secondary molding process, the greater the difference between the primary molding temperature and the secondary molding temperature, the easier it is to obtain a secondary molded body that does not have a distorted shape. The primary molding temperature may be 3° C. or higher, further 5° C. or higher, further 10° C. or higher, further 20° C. or higher, or further 30° C. or higher than the secondary molding temperature. However, in the production method of the present invention, the secondary molding temperature is lower than the primary molding temperature, and the difference is 3 to 30 ° C., further 3 to 20 ° C., further 3 to 10 ° C., or further Even if the temperature is as small as 5 to 10° C., a secondary molded body without distorted shape can be obtained with good reproducibility.

The primary molding temperature and secondary molding temperature may be controlled by the temperature of the mold for the molded product (hereinafter also referred to as "molding mold"). That is, in the molding step, the temperature of the mold for primary molding is set to the temperature of the mold for secondary molding or higher, further 3 ° C. or higher, further 5 ° C. or higher, further 10 ° C. or higher, or further 20 ° C. or higher. Furthermore, by setting the temperature to 30° C. or higher, the secondary molding temperature can be made equal to or lower than the primary molding temperature.

The molding method in the secondary molding step is any one or more of the group consisting of press molding, cold isostatic pressing, cast molding, sheet molding and injection molding, provided that the primary molding temperature and the secondary molding temperature satisfy the above relationship. Any molding method may be used. The molding method is preferably at least one of cast molding and injection molding, since a molded article having an arbitrary shape can be easily obtained. Furthermore, it is more preferable that the molding in the secondary molding step is injection molding, since a molded article having a more complicated and fine shape can be easily obtained with good reproducibility.

For example, the injection pressure in injection molding is 50 MPa or more and 150 MPa or less, and further 70 MPa or more and 130 MPa or less.

The light-colored powder to be subjected to the primary molding process and the secondary molding process (hereinafter also referred to as the "molding process") is a zirconia powder containing colored lanthanide, or a mixed powder of colored lanthanide powder and zirconia powder. good.

The light-colored powder preferably has a BET specific surface area of 7 to 20 m ² /g, more preferably 7.5 to 15 m ² /g. By setting the BET specific surface area within this range, the light-colored compact tends to have the same sintering behavior as the light-colored compact containing alumina.

The zirconia powder can include zirconia powder containing 3 mol % yttria.

If the light colored powder contains alumina, the alumina should be less than the colored lanthanides. Alumina contained in the light-colored powder is 1% by weight or less, further 0.5% by weight or less, further 0.3% by weight or less, or further 0.25% by weight or less with respect to zirconia in the light-colored powder Just do it.

The content of the colored lanthanoid may be 0.1% by weight or more and 6% by weight or less, more preferably 0.3% by weight or more and 3.5% by weight or less, relative to the weight of the light-colored powder.

Any mixing method may be used as long as these powders and the zirconia powder can be uniformly mixed. The mixing method is preferably wet mixing, more preferably ball mill or bead mill. A specific mixing method includes mixing with a ball mill for 24 hours or more.

The light-colored powder to be subjected to the molding step is zirconia powder containing at least alumina, and may be a mixed powder of alumina powder and zirconia powder.

The content of alumina is 0.25% to 20% by weight, further 1% to 20% by weight, and further 5% to 10% by weight with respect to the weight of the light-colored powder. Any of the following is acceptable. As the alumina powder, alumina powder having a purity of 99% or higher, and further a purity of 99.5% or higher can be used.

Zirconia powder can include zirconia powder containing 3 mol % yttria.

In the molding step, at least one of the light-colored powder and the light-colored powder preferably contains an organic binder in order to improve the fluidity of the powder.

When an organic binder is included, the content of the organic binder in each zirconia powder can be 25 to 65% by volume, more preferably 35 to 60% by volume.

At least one selected from the group consisting of acrylic resins, polyolefin resins, waxes and plasticizers can be used as the organic binder.

Any mixing method may be used as long as the zirconia powder and the organic binder can be uniformly mixed. Heat kneading and wet mixing can be exemplified as the mixing method.

It is preferable that the light-colored compact and the light-colored compact have the same sintering shrinkage strength. As a result, the compact can be sintered in a state in which the two are joined together more firmly without distortion caused by the difference in contraction amount.

In the sintering step, the secondary molded body is sintered to obtain a preliminary sintered body.

In the firing step, the firing temperature is 1300° C. or higher, preferably 1350° C. or higher. If the firing temperature is lower than 1300° C., the sintered body will not be densified in the HIP treatment step. The firing temperature need not be higher than necessary, and can be 1300° C. or higher and 1550° C. or lower, further 1350° C. or higher and 1500° C. or lower, or further 1350° C. or higher and 1450° C. or lower.

The sintering atmosphere may be the air, an inert atmosphere, or a vacuum, preferably at least either the air or the inert atmosphere, and more preferably the air. Any combination of the above firing temperature and firing atmosphere can be applied. The sintering step is preferably normal pressure sintering, which is a method of sintering by simply heating without applying an external force to the compact.

Although the firing time varies depending on the firing temperature, it is preferably 1 hour or longer, more preferably 2 hours or longer. When the firing time is 1 hour or longer, the removal of gaps is facilitated in the firing process. On the other hand, the firing time may be 5 hours or less, preferably 3 hours or less.

When a compact is produced from zirconia powder containing an organic binder, a degreasing treatment is performed to remove the organic binder from the compact before firing.

The baking temperature in the degreasing treatment should be 400° C. or higher and 600° C. or lower. Moreover, the atmosphere for the degreasing treatment may be any atmosphere selected from the group consisting of air, an inert gas atmosphere, and an oxidizing gas atmosphere.

In the production method of the present invention, the pre-sintered body is HIP-treated. As a result, elimination of interfacial gaps is facilitated while suppressing color bleeding at the interface, and the pre-sintered body is sintered, thereby obtaining the multicolored zirconia sintered body of the present invention.

In the HIP treatment, the HIP temperature can be 1200° C. or higher, further 1250° C. or higher, further 1300° C. or higher, or further 1350° C. or higher. If the densification progresses, the HIP temperature does not need to be increased more than necessary, and it is preferable that the HIP treatment temperature is lower than the sintering temperature, and that the HIP treatment temperature is 30° C. or more lower than the sintering temperature. The HIP temperature can be 1650° C. or lower, and further 1450° C. or lower.

The HIP pressure is 50 MPa or higher, further 100 MPa or higher, or further 140 MPa or higher. In HIP processing using a normal HIP processing apparatus, the HIP pressure is 250 MPa or less, and further 180 MPa or less.

The HIP treatment atmosphere may be either an inert atmosphere or a weakly reducing atmosphere, and may include at least either a nitrogen atmosphere or an argon atmosphere, preferably an argon atmosphere. The above HIP temperature, HIP pressure and atmosphere, and their upper and lower limits may be combined in any desired manner.

The container in which the secondary molded body is placed during the HIP treatment is preferably a container made of carbon. As a result, even in HIP processing in an argon atmosphere, a weakly reducing atmosphere can be created in the vicinity of the secondary compact.

After the HIP treatment, the obtained HIP-treated body may be sintered in an oxidizing atmosphere, if necessary. The sintering temperature conditions include 600° C. or higher and 1000° C. or lower in the air for 1 to 5 hours.

By the production method of the present invention, it is possible to obtain a multicolored zirconia sintered body without color bleeding and gaps at the interface.

Furthermore, the manufacturing method of the present invention includes at least either a processing step or a polishing step (hereinafter also referred to as a “post-treatment step”) for making the obtained multicolored zirconia sintered body into various members. You can stay.

In the processing step, the multicolored zirconia sintered body obtained by HIP processing is processed into a desired shape. Any processing method can be used. The processing method may be general cutting processing, and examples include any one or more of the group consisting of lathe processing, surface grinding, R grinding and NC processing (numerical control machining). The surface is processed so as to expose the interface between the light-colored sintered body and the light-colored sintered body, and the interface formed by laminating the uneven portions of the light-colored sintered body and the light-colored sintered body is formed on the surface. A multicolor zirconia sintered body in which the interface between the light-colored sintered body and the light-colored sintered body and the light-colored sintered body and the light-colored sintered body form a pattern on the same surface by processing the surface so that it is exposed. can do.

In the polishing step, the multicolored zirconia sintered body obtained by HIP treatment or a processed product thereof is polished. As a result, the gloss can be made stronger, and the high-class feeling of the multicolored zirconia sintered body of the present invention is further emphasized. Although the polishing method is arbitrary, at least one of barrel polishing and R polishing can be exemplified.

In the manufacturing method of the present invention, the primary molding process, secondary molding process, baking process, HIP treatment process, and post-treatment process may be any combination of the above conditions.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to these.
(Sintered compact density and relative density)
The measured density (sintered body density) of the multicolor zirconia sintered body was measured by the Archimedes method. The relative density of the multicolored zirconia sintered body was obtained from the obtained measured density and theoretical density. The theoretical density of the multicolor zirconia sintered body was calculated from the formula (1'). Table 2 shows the calculated theoretical densities of the multicolor zirconia sintered bodies of Examples and Comparative Examples.
(Specific surface area)
The BET specific surface area by nitrogen adsorption was measured and used as the specific surface area of the powder sample. A general specific surface area measuring device (manufactured by QUANTA CHROME) was used for the measurement.
(Optical microscope observation)
The interface of the sintered sample was observed using an optical microscope (apparatus name: MM-800, manufactured by Nikon) or a trinocular zoom stereoscopic microscope (apparatus name: AR-372ZH, manufactured by Arm System Co., Ltd.). In the observation with an optical microscope, the presence or absence of gaps at the interface and the presence or absence of color bleeding were observed.
(SEM observation)
An SEM (device name: JSM-5400, manufactured by JEOL Ltd.) was used to observe the interface of the sintered sample. In the SEM observation, the presence or absence of gaps at the interface was observed at a magnification of 500 times.
(Elemental quantitative analysis by EPMA)
A wavelength dispersive electron probe microanalyzer (EPMA) (device name: EPMA1610, manufactured by Shimadzu Corporation) was used to perform point analysis in the vicinity of the interface of the lanthanide-colored sintered body in the sintered body sample. The measurement conditions are as follows.
Accelerating voltage: 15KV
Irradiation current: 100nA
Analysis range: φ10 μm
Measurement was performed at a distance of 30 μm, 50 μm, 100 μm, 130 μm, 170 μm and 200 μm from the interface to the white sintered body, and the area where the coloring component was confirmed, and the measurement area at the farthest distance from the interface area.

(L ^* a ^* b ^* color tone by color system)
The color tone of the sintered sample was measured according to JISZ8722. A general color difference meter (apparatus name: Color Analyzer TC-1800MK-II, manufactured by Tokyo Denshoku Co., Ltd.) was used for the measurement. The measurement conditions are as follows.
Light source: D65 light source
Viewing angle: 2°
The sintered body sample was a disc having a thickness of 1 mm and a diameter of 20 mm, and had both sides polished.

(Mechanical strength test)
As the mechanical strength of the multicolored zirconia sintered body sample, the impact strength was measured by a rigid ball drop test according to ISO14368-3. That is, a multicolor zirconia sintered sample was placed on a SUS plate. After that, an iron ball weighing 16 g was dropped from a height of 5 cm from the multi-colored zirconia sintered body sample near the interface between the lanthanide-colored sintered body and the dark-colored sintered body, and cracks in the multi-colored zirconia sintered body were detected. , the presence or absence of cracks, cracks and other destruction was confirmed. After that, the falling start position of the iron ball (hereinafter also referred to as "falling ball position") was raised at intervals of 5 cm, and the same measurement was performed. The impact strength of the multicolored zirconia sintered body sample was defined as the falling ball position (cm) at which breakage was confirmed in the multicolored zirconia sintered body.

Example 1
A pink/white zirconia sintered body composed of a pink zirconia sintered body and a white zirconia sintered body was produced.
(Preparation of pink zirconia raw material)
3 mol% having a BET specific surface area of 8 m ² /g and containing 0.25% by weight of alumina so that the weight of erbium with respect to the total weight of yttria and zirconia in the 3 mol% yttria-stabilized zirconia powder is 2% by weight Erbium oxide powder (trade name: erbium oxide, manufactured by Shin-Etsu Chemical) was added to yttria-stabilized zirconia powder (trade name: TZ-3YSE, manufactured by Tosoh Corporation).

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain pink zirconia powder.
The obtained pink zirconia powder was mixed with an acrylic binder to obtain a pink zirconia raw material. The content of pink zirconia powder in the pink zirconia raw material was 45% by volume.

(Preparation of white zirconia raw material)
3 mol% yttria ^- stabilized zirconia powder (trade name: TZ-3YS, manufactured by Tosoh Corporation) was added with commercially available high-purity aluminum oxide powder (purity: 99.9% or more, average particle size: 0.3 μm).

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain a white zirconia powder.
The resulting white zirconia powder was mixed with an acrylic binder to obtain a white zirconia raw material. The content of white zirconia powder in the white zirconia raw material was 45% by volume.

(Preparation of compact)
A bezel-ring-shaped white zirconia molding having projections was obtained by injection molding a white zirconia raw material. The injection molding pressure was 100 MPa.

Next, a pink zirconia raw material was injection molded on the obtained white zirconia molded body. The injection molding pressure was 100 MPa, and the mold temperature was 5° C. lower than the injection molding temperature of the white zirconia raw material. As a result, a molded body was obtained in which the pink zirconia molded body was laminated on the white zirconia molded body and the two were joined together.

The obtained compact was degreased in air at a temperature increase rate of 2.0° C./h, a degreasing temperature of 450° C., and a degreasing time of 4 hours.

(Firing and HIP treatment)
A pre-sintered body was obtained by sintering the compact after degreasing treatment in the atmosphere at a heating rate of 100° C./h, a sintering temperature of 1450° C., and a sintering time of 2 hours.
After placing the obtained pre-sintered body in an alumina container, HIP treatment is performed at a HIP temperature of 1400 ° C., a HIP pressure of 150 MPa, and a holding time of 1 hour in an atmosphere of argon gas with a purity of 99.9%. A HIP-treated body was obtained. The HIP-treated body was used as the pink/white zirconia sintered body of this example. Table 1 shows the evaluation results of this example.

The obtained pink/white zirconia sintered body has a volume ratio of 59:41 to the pink zirconia sintered body and the white zirconia sintered body, and the pink/white zirconia sintered body has a relative density of 99.9. %Met.
(Material processing)
The surface of the pink/white zirconia sintered body of this example on the pink zirconia sintered body side was processed until the protrusions of the white zirconia sintered body were clearly confirmed. As a result, the pink/white zirconia sintered body of this example was made into a bezel ring having a pattern of the white zirconia sintered body on the surface of the pink zirconia sintered body. By polishing the bezel ring after the surface processing, a bezel ring made of the pink/white zirconia sintered body of this example and having a strong glossy feeling was obtained.

The bezel ring has a surface made of a pink zirconia sintered body, and a pattern made of a white zirconia sintered body on the surface, and a pink zirconia sintered body and a white sintered body , the pink zirconia sintered body and the white sintered body were exposed on the same surface to form a pattern.

Moreover, the interface of the said bezel ring was confirmed visually. As a result, it was confirmed that the white color of the interface was not blurred and that the interface had no color bleeding. In addition, as a result of quantitative elemental analysis of the interface by EPMA, the erbium element was not confirmed in the regions of the white sintered body at 30 μm, 50 μm, 100 μm, and 200 μm from the interface, and the coloring component did not seep into the white sintered body side. I was able to confirm that it is not.

Furthermore, the interface of the bezel ring was observed with an optical microscope and SEM observation. A backscattered electron image obtained by SEM observation is shown in FIG. It was confirmed that pink zirconia and white zirconia were sintered to form an interface, that there was no gap at the interface, and that there was no bonding layer (broken circle in FIG. 1).

Furthermore, the obtained bezel ring was subjected to a mechanical strength test. Even if an iron ball was dropped from a height of 85 cm, no cracks or breaks occurred. From this, it was confirmed that the pink/white zirconia sintered body of the present example had an impact strength of 85 cm or more and had high strength.

Example 2
An orange/white zirconia sintered body composed of an orange zirconia sintered body and a white zirconia sintered body was produced.

That is, 3 mol% yttria-stabilized zirconia powder containing 0.25% by weight of alumina and having a BET specific surface area of 8 m ² /g so that the weight of praseodymium is 1% by weight (trade name: TZ-3YSE, Tosoh Corporation company) was added with praseodymium oxide powder (trade name: praseodymium oxide, manufactured by Shin-Etsu Chemical Co., Ltd.).

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain an orange zirconia powder.

An orange/white zirconia sintered body of this example was obtained by molding, firing, and HIP treatment in the same manner as in Example 1, except that the orange zirconia powder was used instead of the pink zirconia powder. . Table 1 shows the evaluation results of this example.

The resulting orange/white zirconia sintered body has a volume ratio of 59:41 to the orange zirconia sintered body and the white zirconia sintered body, and the orange/white zirconia sintered body has a relative density of 99.9. %Met.

Next, the orange/white zirconia sintered body obtained was processed and polished in the same manner as in Example 1 to obtain the orange/white zirconia sintered body of this example, which has a strong luster. Got a bezel ring.

The bezel ring has a surface made of an orange zirconia sintered body, and has a pattern made of a white zirconia sintered body on the surface. The interface with the orange zirconia sintered body and the white sintered body were exposed on the same surface to form a pattern.

The interface of the bezel ring was visually confirmed. As a result, it was confirmed that the white color of the interface was not blurred and that the interface had no color bleeding. In addition, as a result of quantitative elemental analysis of the interface by EPMA, no praseodymium element was confirmed in the regions of the white sintered body at 30 μm, 50 μm, 100 μm, and 200 μm from the interface, and the coloring component did not seep into the white sintered body side. I was able to confirm that it is not.

Furthermore, the interface of the bezel ring was observed with an optical microscope and SEM observation. A backscattered electron image obtained by SEM observation is shown in FIG. It was confirmed that orange zirconia and white zirconia were sintered to form an interface, that there was no gap at the interface, and that there was no binding layer (broken circle in FIG. 5).

Furthermore, the obtained bezel ring was subjected to a mechanical strength test. Even if an iron ball was dropped from a height of 85 cm, no cracks or breaks occurred. From this, it was confirmed that the orange/white zirconia sintered body of the present example had an impact strength of 85 cm or more and had high strength.

Example 3
A disk-shaped lavender/white zirconia sintered body composed of a lavender-colored zirconia sintered body and a white zirconia sintered body was produced.
(Preparation of raw materials)
3 mol% yttria-stabilized zirconia powder (trade name: TZ-3YSE, manufactured by Tosoh Corporation) having a BET specific surface area of 8 m ² /g and containing 0.25% by weight of alumina so that the neodymium weight is 2% by weight ) was added with neodymium oxide powder (trade name: neodymium oxide, manufactured by Shin-Etsu Chemical Co., Ltd.).

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain lavender-colored zirconia powder. The obtained lavender-colored zirconia powder was used as a lavender-colored zirconia raw material, and the white zirconia powder obtained in the same manner as in Example 1 was used as a white zirconia raw material.
(Preparation of compact)
A convex primary molded body was obtained by uniaxially press-molding the white zirconia raw material at room temperature. Lavender-colored zirconia powder was filled on the obtained primary molded body, and the primary molded body and the lavender-colored zirconia powder were uniaxially press-molded at the same time. A secondary compact was obtained by subjecting the compact after uniaxial pressing to cold isostatic pressing (CIP). The CIP treatment pressure was set to 200 MPa, and the molding temperature was set to room temperature or lower.
(Firing and HIP treatment)
A lavender/white zirconia sintered body of this example was obtained in the same manner as in Example 1, except that the obtained secondary compact was used.
(Material processing)
The surface of the lavender-colored zirconia sintered body side of the lavender-colored/white-zirconia sintered body of this example was processed until the protrusions of the white zirconia sintered body were clearly confirmed. As a result, the lavender/white zirconia sintered body of this example was made into a disk-shaped zirconia sintered body having a pattern of the white zirconia sintered body on the surface of the lavender colored zirconia sintered body. By polishing the disk-shaped zirconia sintered body after the surface processing, a disk-shaped zirconia sintered body composed of the lavender/white zirconia sintered body of the present example and having a strong glossy feeling was obtained. The obtained disk-shaped zirconia sintered body had a diameter of 16 mm, a thickness of 2.5 mm, and a pattern width of 3 mm. Table 1 shows the evaluation results of this example.

The disk-shaped zirconia sintered body has a surface made of a lavender-colored zirconia sintered body, and has a pattern made of a white zirconia sintered body on the surface, and a lavender-colored zirconia sintered body and the white sintered body, the lavender-colored zirconia sintered body and the white sintered body were exposed on the same surface to form a pattern.

The interface of the disk-shaped zirconia sintered body was visually confirmed. As a result, it was confirmed that the white color of the interface was not blurred and that the interface had no color bleeding.

Further, the interface of the disk-shaped zirconia sintered body was observed by optical microscope and SEM observation. As a result, it was confirmed that the lavender-colored zirconia and the white zirconia were sintered to form an interface, that there was no gap in the interface, and that there was no bonding layer.

Example 4
A disk-shaped red/white zirconia sintered body composed of a red zirconia sintered body and a white zirconia sintered body was produced.
(Preparation of raw materials)
Reagent-grade cerium oxide powder was added to 3 mol% yttria-stabilized zirconia powder (trade name: TZ-3YS, manufactured by Tosoh Corporation) having a BET specific surface area of 8 m ² /g so that the cerium oxide weight was 1% by weight. (99.9% or higher purity) was added.

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain a red zirconia powder.

The obtained red zirconia powder was used as a red zirconia raw material, and the white zirconia powder obtained in the same manner as in Example 1 was used as a white zirconia raw material.

Molding, firing, and HIP treatment were performed in the same manner as in Example 3, except that the red zirconia powder was used instead of the lavender zirconia powder, and that a breathable carbon container was used during the HIP treatment. A red/white zirconia sintered body of this example was obtained.
Furthermore, the obtained red/white zirconia sintered body was processed in the same manner as in Example 3 to obtain a disk-shaped zirconia sintered body having a diameter of 16 mm, a thickness of 2.5 mm, and a pattern width of 3 mm. . Table 1 shows the evaluation results of this example.

The disk-shaped zirconia sintered body had a surface made of a red zirconia sintered body, and had a pattern made of a white zirconia sintered body on the surface. FIG. 12 shows a photograph of the appearance of the red/white zirconia sintered body of this example. As is clear from FIG. 12(a), in the red/white zirconia sintered body of this example, the interface between the red zirconia sintered body and the white sintered body, the red zirconia sintered body and the white sintered body It has a pattern exposed on the same surface. Furthermore, as is clear from FIG. 12(b), the red/white zirconia sintered body of this example had a structure in which a red zirconia sintered body and a white zirconia sintered body were laminated. From FIGS. 12A and 12B, it can be seen that the protrusions of the white zirconia sintered body and the recesses of the red zirconia sintered body are processed to expose the surface, so that the pattern is on the same surface. It was confirmed that they were formed.

The interface of the disk-shaped zirconia sintered body was visually confirmed. As a result, it was confirmed that the white color of the interface was not blurred and that the interface had no color bleeding.

In addition, as a result of quantitative elemental analysis of the interface by EPMA, the cerium element was not confirmed in the regions of the white sintered body at 30 μm, 50 μm, 100 μm and 200 μm from the interface, and there was no bleeding of the coloring component to the white sintered body side. I was able to confirm that.

Further, the interface of the disk-shaped zirconia sintered body was observed by optical microscope and SEM observation. As a result, it was confirmed that the red zirconia and the white zirconia were sintered to form an interface, that there was no gap in the interface, and that there was no bonding layer.

Example 5
A pink/white zirconia sintered body composed of a pink zirconia sintered body and a white zirconia sintered body was produced.
(Preparation of white zirconia raw material)
3 mol% yttria ^- stabilized zirconia powder (trade name: TZ-3YS, manufactured by Tosoh Corporation) was added with commercially available high-purity aluminum oxide powder (purity: 99.9% or more, average particle size: 0.3 μm).

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain a white zirconia powder.

The obtained white zirconia powder was used as a white zirconia raw material, and the pink zirconia powder obtained in the same manner as in Example 1 was used as a pink zirconia raw material.
A pink/white zirconia sintered body of this example was obtained by molding, firing, and HIP treatment in the same manner as in Example 1, except that the white zirconia powder was used instead of the white zirconia powder.

Further, the obtained pink/white zirconia sintered body was processed in the same manner as in Example 3 to obtain a disk-shaped zirconia sintered body having a diameter of 16 mm, a thickness of 2.5 mm, and a pattern width of 3 mm. rice field. Table 1 shows the evaluation results of this example. The disk-shaped zirconia sintered body has a surface made of a pink zirconia sintered body, and has a pattern made of a white zirconia sintered body on the surface. and the white sintered body, the pink zirconia sintered body and the white sintered body were exposed on the same surface to form a pattern.

The interface of the disk-shaped zirconia sintered body was visually confirmed. As a result, it was confirmed that the white color of the interface was not blurred and that the interface had no color bleeding. In addition, as a result of quantitative elemental analysis of the interface by EPMA, the erbium element was not confirmed in the regions of the white sintered body at 30 μm, 50 μm, 100 μm and 200 μm from the interface, and there was no bleeding of the coloring component to the white sintered body side. I was able to confirm that.

Further, the interface of the disk-shaped zirconia sintered body was observed by optical microscope and SEM observation. As a result, it was confirmed that the pink zirconia and the white zirconia were sintered to form an interface, that there was no gap in the interface, and that there was no bonding layer.

Example 6
An orange/white zirconia sintered body composed of an orange zirconia sintered body and a white zirconia sintered body was produced.
(Preparation of white zirconia raw material)
3 mol% yttria ^- stabilized zirconia powder (trade name: TZ-3YS, manufactured by Tosoh Corporation) was added with commercially available high-purity aluminum oxide powder (purity: 99.9% or more, average particle size: 0.3 μm).

After the addition, these powders were mixed in a ball mill for 24 hours in an ethanol solvent using zirconia balls with a diameter of 10 mm. The mixed powder was dried to obtain a white zirconia powder.

The resulting white zirconia powder was used as a white zirconia raw material, and the orange zirconia powder obtained in the same manner as in Example 2 was used as an orange zirconia raw material. An orange/white zirconia sintered body of this example was obtained by molding, firing, and HIP treatment in the same manner as in Example 2, except that the white zirconia powder was used instead of the white zirconia powder.

Furthermore, the obtained orange/white zirconia sintered body was processed in the same manner as in Example 3 to obtain a disk-shaped zirconia sintered body having a diameter of 16 mm, a thickness of 2.5 mm, and a pattern width of 3 mm. rice field. Table 1 shows the evaluation results of this example.

The disk-shaped zirconia sintered body has a surface made of an orange zirconia sintered body, and has a pattern made of a white zirconia sintered body on the surface. and the white sintered body, the orange zirconia sintered body and the white sintered body were exposed on the same surface to form a pattern.

The interface of the disk-shaped zirconia sintered body was visually confirmed. As a result, it was confirmed that the white color of the interface was not blurred and that the interface had no color bleeding. In addition, as a result of quantitative elemental analysis of the interface by EPMA, no praseodymium element was confirmed in the regions of the white sintered body at 30 μm, 50 μm, 100 μm and 200 μm from the interface, and there was no bleeding of the coloring component to the white sintered body side. I was able to confirm that.

Further, the interface of the disk-shaped zirconia sintered body was observed by optical microscope and SEM observation. As a result, it was confirmed that the orange zirconia and the white zirconia were sintered to form an interface, that there was no gap in the interface, and that there was no bonding layer.

Comparative example 1
According to the method described in Patent Document 3, a multicolor ceramic shaped article was produced.

Two compositions were obtained by mixing 1000 g of 3 mol % yttria-stabilized zirconia powder, a coloring material, and an acrylic binder. A composition using 20 g of FeCrNi spinel as a coloring substance was used as a black zirconia raw material, and a composition using 14 g of CoAl as a coloring substance was used as a blue zirconia raw material.

After injection molding the blue zirconia raw material into a bezel ring-shaped blue zirconia molded body having projections, the black zirconia raw material was injection molded on the blue zirconia molded body under a pressure of 100 MPa. As a result, a molded body was obtained in which the black zirconia molded body was laminated on the blue zirconia molded body and the two were joined together.

After degreasing the resulting compact, it was fired in air at a heating rate of 100° C./h, a firing temperature of 1500° C., and a sintering time of 20 minutes to obtain a multicolor ceramic shaped article of this comparative example. . The obtained ceramic shaped article had a relative density of 99.8%, confirming that it had a high density.

The multicolor ceramic shaped article of this comparative example was subjected to surface processing until the interface between the black zirconia sintered body and the blue zirconia sintered body could be confirmed, and the interface was observed with an optical microscope and SEM. The observation result of the optical microscope is shown in FIG. 13(a). From FIG. 13(a), it was confirmed that a gap was generated between the black zirconia sintered body and the blue zirconia sintered body (arrow portion in FIG. 13(a)). An SEM observation diagram of the gap is shown in FIG. 13(b). It was confirmed that the gap had a width of 40 μm or more.

Comparative example 2
A multicolor ceramic molded article of this comparative example was produced in the same manner as in Comparative Example 1 except that the firing time was set to 2 hours, and the interface between the black zirconia sintered body and the blue zirconia sintered body was confirmed by SEM. . The results are shown in FIG.

From FIG. 14, it was confirmed that a gap exceeding 40 μm was generated between the black zirconia sintered body and the blue zirconia sintered body. Also, by visual observation, it was confirmed that the interface was blurred in blue, and that the interface had color bleeding.

Comparative example 3
A multicolor ceramic shaped article of this comparative example was produced in the same manner as in Comparative Example 1, except that the firing time was set to 4 hours. FIG. 15 shows the appearance of the multicolor ceramic shaped article obtained, and FIGS. 16 and 17 are optical microscope photographs of the interface between the black zirconia sintered body and the blue zirconia sintered body.

FIG. 15(a) is an external view of a multicolor ceramic molded article, and FIG. 15(b) is an enlarged view of a dashed square portion of FIG. 15(a). From FIG. 15(a), it was confirmed visually that there is a color tone different from black and blue in appearance between the black zirconia sintered body and the blue zirconia sintered body (arrow part in FIG. 15(a) ). From FIG. 15(b), it can be confirmed that there are five diagrams having a substantially rectangular parallelepiped shape and different widths, and furthermore, it can be confirmed that the portions with color tones different from black and blue are gaps (FIG. 15(b) arrow).

The thinnest approximately rectangular parallelepiped diagram with a width of 0.2 mm and a length of 3 mm (broken circle in FIG. 15(b)) has a clearly different color tone from the other diagrams, and the pattern is unclear due to color bleeding. had become In addition, it was confirmed that there was color bleeding near the interface in all other diagrams with widths of 0.3 mm to 3 mm.

Moreover, FIG. 16 is an optical microscope photograph of another part of the multicolored zirconia modeled article of this comparative example. From FIG. 16, it was confirmed that a gap was generated between the black zirconia sintered body and the blue zirconia sintered body (indicated by an arrow in FIG. 16). In addition, from FIG. 17, it was possible to confirm the interface of the multicolor ceramic molded product of this comparative example, but it can be confirmed that the interface itself has a width and color bleeding occurs (broken line square in FIG. 17) ). From this, it was confirmed that the ceramic shaped article of this comparative example had both gaps and color bleeding at the interface.

From the results of Comparative Examples 1 to 3, it can be confirmed that in the control by the firing time, a clear interface is formed by insufficient sintering, and has both gaps and color bleeding. It was confirmed that the interface became unclear due to color blurring as the deterioration progressed.

The zirconia sintered body of the present invention can be widely used for watch parts, decorative articles, mobile device parts, vehicle parts, luxury daily parts, and the like. In particular, the zirconia sintered body of the present invention is used for watch parts such as watch bands, bezels, dials and watch cases, decorative parts such as brooches, tie pins, metal fittings for handbags, and bracelets, housings for mobile electronic devices, lighter cases, and cosmetics. It can be used for exterior parts such as cases, mobile phone cases, and earphone housings, as well as daily necessities such as knives and cooking utensils, as well as logo marks for various products.

(1) Light-colored sintered body (2) Light-colored sintered body (3) Interface (4) Zirconia sintered body containing no coloring agent (5) Colored Zirconia sintered body (6): A region (7) of the light-colored sintered body at a certain distance from the interface: A circle with a diameter of 10 μm formed around the region of the light-colored sintered body at a certain distance from the interface

Claims (9)

A zirconia sintered body including a first zirconia sintered body and a second zirconia sintered body, wherein the first zirconia sintered body contains Ce, Pr, Nd, Eu, Tb, Ho, Er, Yb and Gd A zirconia sintered body containing one or more lanthanoids selected from the group consisting of: The second zirconia sintered body is a zirconia sintered body containing at least aluminum oxide, and the first zirconia sintered body The body and the second zirconia sintered body form a grain boundary, and the grain boundary is confirmed by at least one of a secondary electron image and a backscattered electron image obtained by SEM observation at a magnification of 500 times or less. A zirconia sintered body characterized in that it does not have gaps that can be formed , and color bleeding that can be confirmed visually or by observing with an optical microscope at a magnification of 10 to 100 times . The zirconia according to claim 1, wherein one of the first zirconia sintered body and the second zirconia sintered body forms a pattern on the surface of the other zirconia sintered body. Sintered body. The zirconia sintered body according to claim 1 or 2, having a relative density of 99.5% or more. The zirconia sintered body according to any one of claims 1 to 3, wherein the lanthanoid contained in said first zirconia sintered body is at least one selected from the group consisting of Ce, Pr, Nd and Er. The zirconia sintered body according to any one of claims 1 to 4, wherein the first zirconia sintered body has a lanthanoid content of 0.1% by weight or more and 6% by weight or less. The zirconia sintered body according to any one of claims 1 to 5, wherein the first zirconia sintered body contains alumina. 7. The zirconia sintered body according to claim 6, wherein said first zirconia sintered body contains 1% by weight or less of alumina relative to zirconia in said first zirconia sintered body. The zirconia sintered body according to any one of claims 1 to 7, wherein the second zirconia sintered body contains 0.25 wt% or more and 20 wt% or less of aluminum oxide. A member comprising the zirconia sintered body according to any one of claims 1 to 8.

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