JP6331840B2 - Red zirconia sintered body and manufacturing method thereof - Google Patents

Description

  The present invention relates to a red zirconia sintered body for use in the exterior of a decorative member and an electronic device material, and particularly to provide a red zirconia sintered body exhibiting a red color and having high strength.

  Zirconia sintered body has been used mainly as a structural member and grinding media because of its high strength, but its beauty of surface gloss after mirror polishing is expected to be applied to decorative parts and exterior parts of electronic equipment materials. ing. In order to cope with such widespread applications, a colored zirconia sintered body excellent in aesthetics is desired.

  So far, red zirconia sintered bodies have been proposed, but those having sufficient aesthetics and strength have not been obtained.

  So far, the following red zirconia sintered bodies have been proposed.

For example, a translucent zirconia sintered body using reduced ceria (Ce ₂ O ₃ ) as a colorant has been proposed (for example, Patent Document 1). However, although it is red, the crystal structure is cubic in order to obtain translucency, there is a problem that the strength is low.

Further, a sintered body using high-strength zirconia mainly composed of tetragonal crystals and reduced ceria (Ce ₂ O ₃ ) as a colorant has been proposed (for example, Patent Document 2). However, the color tone was brown.

  In addition, a sintered body using gold nanoparticles coated with silica has been proposed (for example, Patent Document 3). However, since gold nanoparticles are used, there are problems in terms of cost, and specific numerical values are not described for the color tone and strength of the obtained sintered body.

  As described above, the conventional red zirconia sintered body does not achieve both red coloration and high strength. Therefore, a high-strength red zirconia sintered body having a red color and a pearly luster excellent in balance of brightness, hue, and saturation has not been obtained.

  The present invention solves the problems of such a conventional red zirconia sintered body, and particularly provides a red zirconia sintered body having high strength and excellent aesthetics.

JP 2011-207745 A JP-A-62-83366 JP 2008-031039 A

  The present invention provides a red zirconia sintered body that not only exhibits red color but also has high strength.

The present inventors diligently studied a colored high-strength zirconia sintered body exhibiting a red color. As a result, a zirconia sintered body containing yttria (Y ₂ O ₃ ) is added with a cerium oxide as a colorant, and further imparts a translucency to obtain a red zirconia sintered body without impairing the strength. I found out that

That is, the present invention contains 2 mol% or more and less than 6 mol% of yttria and CeO ₂ 0.3 mol% to 1.5 mol% of cerium oxide, and has a total light transmittance at a sample thickness of 0.5 mm and a measurement wavelength of 550 nm. It is a red zirconia sintered body characterized by being less than 1.5%, having a total light transmittance of 8% or more at a measurement wavelength of 600 nm, and having an average particle diameter of crystal grains of 2 μm or less.

  Conventionally, it has been studied to add trivalent cerium as a colorant to a high-strength zirconia sintered body (containing 2 mol% or more and less than 6 mol% of yttria), but the color tone is brown and not red. However, the present inventors have found that the zirconia sintered body is colored in red without impairing the strength by imparting a translucency to the high-strength zirconia sintered body, and the present invention has been completed. .

  Hereinafter, the red zirconia sintered body of the present invention will be described.

  The red zirconia sintered body of the present invention contains 2 mol% or more and less than 6 mol%, preferably 2 mol% to 4 mol% of yttria. Yttria is a zirconia stabilizer. By containing yttria, the crystal structure of the zirconia sintered body is stabilized. Furthermore, the crystal phase of a zirconia sintered compact can be mainly made into a tetragonal crystal by making yttria content into this range. If the yttria content is less than 2 mol%, the tetragonal crystals in the sintered body tend to transition to monoclinic crystals, and the sintered body may be destroyed during production or under hydrothermal conditions. On the other hand, when the yttria content is 6 mol% or more, the ratio of cubic crystals in the crystal phase increases and the strength decreases.

The yttria content is determined by Y ₂ O ₃ / (ZrO ₂ + Y ₂ O ₃ + CeO ₂ ).

Red zirconia sintered body of the present invention contain 0.3mol% ~1.5mol% cerium oxide in terms of CeO _2. Furthermore, it is preferable that content of a cerium oxide is 0.5 mol%-1 mol%. Cerium oxide functions as a colorant for developing a red color. By containing the cerium oxide in the above range, it becomes possible for the zirconia sintered body to develop a red color having an excellent color tone. On the other hand, if the cerium oxide content is less than 0.3 mol%, the red coloring of the present invention cannot be obtained. If it exceeds 1.5 mol%, the coloring becomes strong and blackening tends to occur.

The content of cerium oxide _is obtained by _{CeO 2 / (ZrO 2 + Y} 2 O 3 + CeO 2).

  In the red zirconia sintered body of the present invention, the cerium oxide needs to contain trivalent cerium. Trivalent cerium is contained in the zirconia sintered body as an oxide of trivalent cerium. By containing trivalent cerium, absorption of light of 380 to 550 nm is improved and a red color is exhibited.

  The more trivalent cerium, the more red the color is displayed. Therefore, trivalent cerium is preferably 10 mol% or more, more preferably 20 mol% or more of cerium in the cerium oxide. If the trivalent cerium in the cerium oxide is less than 10 mol%, the amount of cerium that does not participate in red-specific absorption increases, which makes it difficult to adjust the color tone.

The ratio (%) of trivalent cerium here is the molar fraction (mol%) occupied by trivalent cerium with respect to the cerium oxide contained in the zirconia sintered body. The proportion of trivalent cerium can be determined from CeO _1.5 / (CeO _1.5 + CeO ₂ ). Therefore, the trivalent cerium oxide also has the same ratio (mol%). The amount of trivalent cerium can be calculated by measuring the weight reduction amount before and after the HIP treatment, considering the reduction amount of cerium oxide.

Thus, the red zirconia sintered body of the present invention is different from the colored zirconia sintered body utilizing the color developed by the existing colorant (cerium oxide (CeO ₂ )) itself, that is, the color developed by tetravalent cerium.

  The red zirconia sintered body of the present invention contains a stabilizer other than yttria in a range that does not greatly reduce the strength and does not impair the color tone, such as lanthanoid rare earth oxides, Ca, Mg and oxides thereof. It may be.

  Moreover, in order to adjust a red color tone, you may contain coloring agents other than a cerium oxide. Examples of the colorant for adjusting the red color tone include lanthanoid rare earth oxides such as neodymium oxide and transition metal oxides such as cobalt oxide. The colorant for adjusting the red color tone is preferably neodymium oxide or cobalt oxide, or both.

  The total content of these stabilizers and colorants for adjusting the red color tone is preferably 1 mol% or less, more preferably 0.5 mol% or less, and 0.1 mol% or less. More preferably it is. When the content is 1 mol% or less, these compounds do not precipitate and can be dissolved in the zirconia sintered body, so that the influence on the strength and color tone is small.

The content of the stabilizer other than yttria and the colorant for adjusting the red color tone is a ratio to the zirconia sintered body, and is obtained by X / (ZrO ₂ + Y ₂ O ₃ + CeO ₂ + X) ( X is a stabilizer other than yttria and a colorant for adjusting the red color tone).

  The red zirconia sintered body of the present invention has a sample thickness of 0.5 mm, a light transmittance of less than 1.5% at a measurement wavelength of 550 nm, preferably 1% or less, and a total light transmittance of 8% or more at a measurement wavelength of 600 nm. , Preferably 10% or more, particularly preferably 12 to 30%. In a sample having a thickness of 0.5 mm, the maximum value of the total light transmittance for visible light having a wavelength of 600 nm to 800 nm is preferably 25% or more, more preferably 30% or more, and 35% or more. Is more preferable. When the maximum value of the total light transmittance with respect to visible light having a wavelength of 600 nm to 800 nm is less than 25%, the translucency is low and the aesthetic property is inferior.

  Thus, the red zirconia sintered body of the present invention has a high maximum value of total light transmittance for visible light having a wavelength of 600 nm to 800 nm. Therefore, the red zirconia sintered body of the present invention is a zirconia sintered body having translucency.

The color tone of the colored zirconia sintered body is defined by lightness L ^* and hues a ^* and b ^* . Here, when the lightness L ^* value increases, the color tone becomes brighter, and conversely, when the L ^* value decreases, the color tone becomes darker.
The hue a ^* indicates a color tone from red to green. The larger the a ^* value, the stronger the red tone, and the smaller the value, the stronger the green tone. On the other hand, b ^* values indicate the color tone of the blue from yellow, b ^* values of yellow color tone becomes stronger the larger, the color tone of the blue becomes stronger as the b ^* value is small.

The red zirconia sintered body of the present invention is a translucent zirconia sintered body, a so-called translucent zirconia sintered body. Therefore, the color tone of the red zirconia sintered body of the present invention changes depending on translucency. For example, as the total light transmittance increases, the lightness L ^* decreases and the hue a ^* / b ^* increases. Conversely, when the total light transmittance is reduced, the lightness L ^* is increased and the hue a ^* / b ^* is decreased.

The color tone can be achieved in a range of translucent red zirconia sintered body has the present ^{invention, 10 ≦ L * ≦ 40,20 ≦} a * ≦ 60,10 ≦ b * ≦ 60, a * / b * ≧ 0.8 is preferred, ^{more, 10 ≦ L * ≦ 40,20 ≦} a * ≦ 60,10 ≦ b * ≦ 60, a * / b * ≧ 1 is preferred.

When the a ^* / b ^* ratio is 0.8 or more, yellowish red, and when the a ^* / b ^* ratio is 1 or more, redness increases. Particularly preferably, 20 ≦ L ^* ≦ 40, 20 ≦ a ^* ≦ 60, 10 ≦ b ^* ≦ 60, a ^* / b ^* ≧ 0.8, and further 20 ≦ L ^* ≦ 40, 20 ≦ a ^*. ≦ 60, 10 ≦ b ^* ≦ 60, a ^* / b ^* ≧ 1. When L ^* is 20 or more, the brightness increases and the color becomes bright red.

  The red zirconia sintered body of the present invention preferably has a tetragonal fluorite structure. High strength is obtained by being a tetragonal crystal.

  The average particle size of the crystal particles in the red zirconia sintered body of the present invention is preferably 2 μm or less, and the average particle size is preferably 1 μm or less. When the average particle diameter exceeds 2 μm, the bending strength of the zirconia sintered body tends to be lowered.

  The biaxial bending strength of the red zirconia sintered body of the present invention is preferably 800 MPa or more, more preferably 1000 MPa or more, and particularly preferably 1500 MPa or more.

  Next, the manufacturing method of the red zirconia sintered compact of this invention is demonstrated.

The red zirconia sintered body of the present invention forms yttria of 2 mol% or more and less than 6 mol% and zirconia powder containing 0.3 mol% to 1.5 mol% of cerium oxide in terms of CeO ₂ , and this is subjected to primary sintering. It can be produced by producing trivalent cerium in the sintered body by hot isostatic pressing (HIP) treatment.

  The method of the present invention forms a raw material powder containing zirconia, yttria, and cerium oxide.

The zirconia powder used for the raw material is preferably easily sinterable. For example, a specific surface area of ^{5m 2} / ^g~20m 2 / g, it is preferable to use a powder comprising fine particles of crystallite size 10 nm to 100 nm, a specific surface area of ^{7m 2} / ^g~15m 2 / g, crystallite size 10 nm to 100 nm It is more preferable to use a powder comprising the fine particles. Further, it is more preferable to use a powder in which 2 mol% or more and less than 6 mol% of yttria is dissolved in advance with respect to zirconia. As such a powder, an easily sinterable powder in which 3 mol% of yttria produced by a hydrolysis method is dissolved can be used.

  The purity of the zirconia powder is preferably 99.6 wt% or more, and more preferably 99.8 wt% or more. In particular, the aluminum content is preferably less than 0.1 wt% in terms of oxide. When the purity is less than 99.6 wt% or the aluminum content is 0.1 wt% or more, the light transmittance of the sintered body is affected and the color tone is deteriorated.

  The addition method of the cerium oxide contained in a zirconia powder should just be mixed with said zirconia powder so that it may become the composition range of this invention, The addition method is not limited. In this case, it is preferable to use a cerium oxide powder having a purity of 99.9 wt% or more and an average particle diameter of 2 μm to 3 μm, and more preferably a powder made of fine particles having an average particle diameter of 1 μm.

  The mixing method of the powder is not limited as long as these components are uniformly mixed, and a normal wet mixing method such as a ball mill or a stirring mill can be used.

  There is no particular limitation on the raw material powder as long as it can be formed into a desired shape, and it can be performed by a conventional ceramic forming method such as die pressing, cold isostatic pressing, slip casting, injection molding or the like.

  The obtained molded body is then sintered at normal pressure and in the atmosphere to obtain a primary sintered body. The primary sintering can be performed in the atmosphere using a normal sintering furnace.

  The primary sintering temperature is preferably 1250 ° C. or higher and 1450 ° C. or lower. It is more preferable that the temperature is 1300 ° C. or higher and 1400 ° C. or lower. If the temperature is lower than 1250 ° C., the relative density of the obtained primary sintered body tends to be as low as 95% or less, so that the density of the zirconia sintered body after the HIP treatment is hardly increased. Moreover, when it exceeds 1450 degreeC, the crystal grain diameter of a primary sintered compact will become large too much, and the translucency of the zirconia sintered compact after a HIP process will fall easily. Moreover, high temperature is required for the HIP treatment, and the blackness of the obtained sintered body becomes too strong.

  The average crystal grain size of the primary sintered body is preferably 2 μm or less, more preferably 1.5 μm or less, and further preferably 1 μm or less. If the average crystal grain size exceeds 2 μm, the density of the zirconia sintered body after the HIP treatment tends to be low.

  In the method for producing a red zirconia sintered body of the present invention, the primary sintered body is subjected to HIP treatment.

  In the HIP treatment, tetravalent cerium in the primary sintered body is reduced to produce trivalent cerium. By containing trivalent cerium, the sintered body is colored red.

  The HIP treatment is preferably performed by placing a primary sintered body in a lidded container having a carbon vent. Thereby, the production | generation to trivalent cerium is accelerated | stimulated. The container having air permeability is not particularly limited as long as it is a container other than a sealed container, and examples thereof include open containers such as a lidded container having a ventilation hole and a container without a lid.

  The reason why the formation of trivalent cerium is promoted by using such a container is unclear, but is considered as follows. That is, when cerium is reduced during the HIP process, the reaction of the formula (1) occurs and oxygen is released.

CeO ₂ → 1 / 2Ce ₂ O ₃ + ¼O ₂ ↑ (1)
When oxygen generated by the above reaction stays in the closed container, the primary sintered body is oxidized. Thereby, the production | generation of trivalent cerium is suppressed. By using an air permeable container, oxygen present in the vicinity of the primary sintered body is removed, and generation of trivalent cerium is promoted.

  The HIP treatment is preferably performed in a strong reducing atmosphere, and a non-oxidizing gas such as argon or nitrogen is preferably used as the pressure medium. Moreover, it is preferable to use the apparatus whose heating source and heat insulating material are made of graphite.

  The HIP treatment temperature is preferably 1350 ° C. or higher and lower than 1475 ° C., more preferably 1400 ° C. or higher and 1450 ° C. or lower. Below 1350 ° C., trivalent cerium is hardly formed. On the other hand, when the HIP processing temperature is 1475 ° C. or higher, the blackness becomes too strong. Even if the HIP-treated body that has become blackened once is annealed (heat treatment in an oxidizing atmosphere), the blackness exhibited by the zirconia sintered body is difficult to remove and the red color tone is difficult to improve. Time is required and productivity is inferior.

Note that the higher the HIP processing temperature, the smaller the brightness L ^* of the resulting zirconia sintered body, and the higher the ratio of a ^* value / b ^* value, which is the hue, is likely to be deep red.

  The HIP processing pressure is preferably 50 MPa or more and 200 MPa or less. If it is less than 50 MPa, a pressurizing effect cannot be obtained, and the density of the zirconia sintered body is difficult to improve. On the other hand, when the pressure is 200 MPa or less, densification of the zirconia sintered body is easily promoted.

  Since the red zirconia of the present invention has moderate translucency, in addition to red coloration due to reflection of natural light or illumination light, for example, irradiation of LED light or the like from the back side, reflection of white material or the like on the back side By arranging the material, it is possible to emphasize the red color or adjust the color tone of the red color without recognizing the parts installed on the back surface.

  According to the present invention, a high-strength red zirconia sintered body having a deep red color and transparency can be obtained in addition to diamond luster based on a high refractive index peculiar to zirconia.

The graph which shows the total light ray transmittance (Example 3 and Example 10) of the red zirconia sintered compact of this invention with respect to the light with a wavelength of 200 nm-800 nm. The graph which shows the X-ray-diffraction pattern ((a) Example 3 (b) Example 10) of the red zirconia sintered compact of this invention. The graph which shows the total light transmittance (Comparative Example 1 and Comparative Example 2) of the comparative example with respect to the light with a wavelength of 200-800 nm.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.

  A method for measuring the characteristics of the sintered body and powder of the present invention will be described below.

(Measurement of color tone)
The color tone was measured using a color difference meter (Spectrophotometer SD 3000, manufactured by Nippon Denshoku Industries Co., Ltd.) under the conditions of a D65 light source and a 10 ° viewing angle in accordance with JISZ8722.

(Total light transmittance)
The transmittance was measured based on JISK7105 “Testing method for optical properties of plastics” and JISK7361-1 “Testing method for total light transmittance of plastics and transparent materials”. The measurement sample was processed to have a sintered body thickness of 0.5 mm and mirror-polished to a surface roughness Ra = 0.02 μm or less. For the measurement, a double beam spectrophotometer (manufactured by JASCO Corporation, model V-650) is used, and the light generated from the light source (deuterium lamp and halogen lamp) is transmitted and scattered through the sample, and an integrating sphere is used. The total light transmittance was measured. The measurement wavelength region was 200 nm to 800 nm.

(Biaxial bending strength)
The strength of the sintered body was evaluated according to ISO / DIS6872, using a cylindrical sintered body having a diameter of 16 mm and a thickness of 2 mm.

(Average particle size of crystal particles)
The average particle size of the crystal particles was measured by the intercept method (k = 1.78) after thermally etching the mirror-polished sintered body, taking a 20,000-times photograph with a scanning microscope. The number of particles measured was 200 or more.

Examples 1-4
(Preparation of raw material powder)
Predetermined amounts of zirconia powder and cerium oxide powder were weighed and ball mill mixed with zirconia balls having a diameter of 10 mm in an ethanol solvent for 24 hours, followed by drying to prepare raw material powders having different cerium contents.

As zirconia powder, 3 mol% yttria-containing zirconia powder (manufactured by Tosoh Corporation, TZ-3Y; specific surface area 13 m ² / g, purity 99.8 wt% or more, alumina less than 0.1 wt%) was used as the zirconia powder. used. As the cerium oxide powder, a reagent having a purity of 99.9 wt% was used.

(Primary sintering)
Each raw material powder was molded by a mold press at a pressure of 50 MPa, and then processed at a pressure of 200 MPa using a cold isostatic press, to obtain a cylindrical molded body having a diameter of 20 mm and a thickness of 3 mm. The obtained molded body was sintered in the air at a heating rate of 100 ° C./h, a sintering temperature of 1400 ° C. for a sintering time of 2 hours, allowed to cool naturally, and subjected to primary sintering of sample numbers 1 to 4 Got the body. The characteristics of the obtained primary sintered body are shown in Table 1. The composition of any primary sintered body was the same as that of the raw material powder. Moreover, the relative density of all the primary sintered bodies was 95% or more. The color tone of the sintered body was light yellow due to absorption of tetravalent cerium.

（ＨＩＰ処理）
試料番号１〜４の一次焼結体を用い、温度１４００℃、圧力１５０ＭＰａ、保持時間１時間でＨＩＰ処理した。圧力媒体には純度９９．９％のアルゴンガスを用いた。ＨＩＰ装置はカーボンヒーター及びカーボン断熱材を備えた装置であった。また、試料を設置する容器としてカーボン製蓋付きルツボを用い、通気性を確保した。

(HIP processing)
Using the primary sintered bodies of sample numbers 1 to 4, HIP treatment was performed at a temperature of 1400 ° C., a pressure of 150 MPa, and a holding time of 1 hour. Argon gas having a purity of 99.9% was used as the pressure medium. The HIP apparatus was an apparatus equipped with a carbon heater and a carbon heat insulating material. In addition, a crucible with a carbon lid was used as a container for installing the sample to ensure air permeability.

  The zirconia sintered body obtained by the HIP treatment exhibited a red color. Table 2 shows the characteristics of the obtained zirconia sintered body.

得られたジルコニア焼結体は、５５０ｎｍ以下の波長光は赤色に基づく吸収のため透過せず、５５０ｎｍでの全光線透過率は１．０％以下であった。また、全てのジルコニア焼結体の結晶構造は主に正方晶蛍石型構造であった。実施例３の全光線透過率を図１に、ＸＲＤを図２に示した。

The obtained zirconia sintered body did not transmit light having a wavelength of 550 nm or less due to absorption based on red, and the total light transmittance at 550 nm was 1.0% or less. The crystal structure of all the zirconia sintered bodies was mainly a tetragonal fluorite structure. The total light transmittance of Example 3 is shown in FIG. 1, and the XRD is shown in FIG.

Examples 5-8
Zirconia sintered bodies were obtained in the same manner as in Examples 1 to 4 except that the primary sintered bodies of sample numbers 1 to 4 were used and the HIP treatment temperature was changed to 1450 ° C. The color tone of the sintered body was pale yellow. The properties of the obtained zirconia sintered body are shown in Table 3.

  The obtained zirconia sintered body was a transparent zirconia sintered body having a low brightness and a deep red color compared to the zirconia sintered bodies of Examples 1 to 4. Further, the crystal phase of any sintered body was mainly a tetragonal fluorite structure.

実施例９
（原料粉末の調製）
ジルコニア粉末としては、２ｍｏｌ％イットリア含有ジルコニア粉末（東ソー製；比表面積１３ｍ^２／ｇ、純度９９．８ｗｔ％以上、アルミナ０．１ｗｔ％未満）、４ｍｏｌ％イットリア含有ジルコニア粉末（東ソー製；比表面積１３ｍ^２／ｇ、純度９９．８ｗｔ％以上、アルミナ０．１ｗｔ％未満）を使用した以外は実施例１〜４と同様に原料粉末を得た。

Example 9
(Preparation of raw material powder)
As the zirconia powder, 2 mol% yttria-containing zirconia powder (manufactured by Tosoh; specific surface area 13 m ² / g, purity 99.8 wt% or more, alumina less than 0.1 wt%), 4 mol% yttria-containing zirconia powder (manufactured by Tosoh; specific surface area 13 m) ² / g, purity 99.8 wt% or more, alumina less than 0.1 wt%) were used, and raw material powder was obtained in the same manner as in Examples 1-4.

(Primary sintering)
The raw material powder was molded at a pressure of 50 MPa by a die press and then processed at a pressure of 200 MPa using a cold isostatic press to obtain a cylindrical molded body having a diameter of 20 mm and a thickness of 3 mm.

  Primary sintering was performed in the air at a rate of temperature increase of 100 ° C./h, a sintering temperature of 1400 ° C., and a sintering time of 2 hours to obtain primary sintered bodies of sample numbers 9 and 10. The composition of the primary sintered body was the same as that of the raw material powder. The color tone of the sintered body was pale yellow.

  The characteristics of the obtained primary sintered body are shown in Table 4.

（ＨＩＰ処理）
試料番号９、１０の一次焼結体を用い、温度１４００℃、圧力１５０ＭＰａ、保持時間１時間で、実施例１〜４と同様の方法でＨＩＰ処理した。

(HIP processing)
Samples 9 and 10 were subjected to HIP treatment in the same manner as in Examples 1 to 4 at a temperature of 1400 ° C., a pressure of 150 MPa, and a holding time of 1 hour.

  The properties of the obtained zirconia sintered body are shown in Table 5. The total light transmittance of Example 10 is shown in FIG. 1, and the XRD is shown in FIG.

比較例１
酸化セリウムの含有量を１．６ｍｏｌ％とした以外は実施例１〜４と同様にして焼結体を得た。

Comparative Example 1
A sintered body was obtained in the same manner as in Examples 1 to 4, except that the content of cerium oxide was 1.6 mol%.

  The characteristics of the obtained zirconia sintered body are shown in Table 6. The obtained sintered body was strong in blackness because of its high cerium content. The total light transmittance of Comparative Example 1 is shown in FIG.

Comparative Example 2
Using a primary sintered body of sample number 3, HIP treatment was performed in the same manner as in Examples 1 to 4 at a temperature of 1600 ° C., a pressure of 150 MPa, and a holding time of 1 hour. Since the obtained sintered body had a high HIP temperature and was black, annealing was performed in the atmosphere at 900 ° C. for 2 hours, but it was black.

  The characteristics of the obtained zirconia sintered body are shown in Table 6. The total light transmittance of Comparative Example 2 is shown in FIG.

Comparative Example 3
The raw material powder having the composition of Sample 3 was molded at a pressure of 50 MPa by a die press, and then processed at a pressure of 200 MPa using a cold isostatic press to obtain a cylindrical molded body having a diameter of 20 mm and a thickness of 3 mm.

  Sample 3 was put in a container together with carbon, and reduced and fired in argon at a rate of temperature increase of 100 ° C./h, a sintering temperature of 1400 ° C., and a sintering time of 2 hours to obtain a sintered body. The color tone of the obtained sintered body was ocher because HIP treatment was not performed.

  The properties of the obtained sintered body are shown in Table 6.

  The red zirconia sintered body of the present invention is a high-density sintered body exhibiting a red hue and excellent in aesthetics, and is a member such as a high-quality jewelry and decorative member that is not damaged, such as a watch. It can be used for various members such as parts and exterior parts of portable electronic devices.

Claims (7)

Containing 0.3mol% ~1.5mol% cerium oxide yttria and CeO ₂ in terms of less 2 mol% or more 6 mol%, the sample thickness 0.5 mm, total light transmittance at a measurement wavelength of 550nm less than 1.5% A red zirconia sintered body characterized in that the total light transmittance at a measurement wavelength of 600 nm is 8% or more and the average particle diameter of crystal grains is 2 μm or less. Lightness ^{L *,} wherein the hue ^{a *} and ^{b *,} characterized in that it is ^{10 ≦ L * ≦ 40,20 ≦ a} * ≦ 60,10 ≦ b * ≦ 60 and ^a * / ^{b *} ≧ 0.8 Item 2. The red zirconia sintered body according to Item 1. Zirconia powder containing yttria of 2 mol% or more and less than 6 mol% and cerium oxide of 0.3 mol% to 1.5 mol% in terms of CeO ₂ is molded, and subjected to primary sintering and hot isostatic pressing. The method for producing a red zirconia sintered body according to claim 1 or 2.   The method for producing a red zirconia sintered body according to claim 3, wherein the temperature during the hot isostatic pressing is 1350 ° C or higher and lower than 1475 ° C.   A member comprising the red zirconia sintered body according to claim 1.   A jewelery using the member according to claim 5.   An exterior component using the member according to claim 5.

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