JP5655512B2 - Colored translucent zirconia sintered body, method for producing the same, and use thereof - Google Patents

Description

  The present invention relates to a colored translucent zirconia sintered body having both a deep color tone and high translucency, and a method for producing the same.

  Conventionally, zirconia single crystals, so-called cubic zirconia, have been used for decorative applications and jewelry applications. Furthermore, cubic zirconia colored by adding a colorant such as a transition metal or a rare earth element is also used for the same purpose (Non-Patent Document 1).

  In these cubic zirconia, a bulk body of zirconia single crystal was first prepared by a skull melt method or the like, and then the manufactured bulk body had to be processed into a target shape by cutting or polishing. Therefore, it is difficult to process cubic zirconia into an arbitrary shape, and cubic zirconia can be used for applications that require high design such as complex shapes or applications that require fine processing. could not.

  On the other hand, a translucent zirconia sintered body obtained by molding and firing zirconia powder and having high transparency has been reported (Patent Document 1, Patent Document 2, Patent Document 3, and Non-Patent Document 2). Since these translucent zirconia sintered bodies can be produced by molding such as injection molding, they can be easily obtained as sintered bodies of any shape. Such a translucent zirconia sintered body having high transparency can be a member having a shape that cannot be processed by cubic zirconia.

  In order to further improve the design of the translucent zirconia sintered body, a translucent zirconia sintered body to which a rare earth oxide is added as a colorant, so-called colored translucent zirconia sintered body has been studied (patent document). 1-3). However, the maximum amount of the colorant that can be contained in the translucent zirconia sintered body while maintaining high transparency is 3 mol% at maximum, and such translucent zirconia sintered body has a weak color tone (patent) Literatures 1-3).

JP 2007-246384 A JP 62-091467 A JP 2010-47460 A

Journal of the Electrochemical Society, Vol. 4, page 962 (1983) Journal of the European Ceramic Society, 29, 283 (2009)

  In order to use the conventional colored translucent zirconia sintered body as a member exhibiting a clear color tone, it is necessary to increase the thickness of the sintered body. Therefore, it is necessary to enlarge the colored translucent zirconia sintered body in order to increase the color tone of the exterior member such as an electronic device that tends to be miniaturized.

  The present invention is a colored translucent zirconia sintered body that has a clear color tone and high transparency as a fine member, and is excellent in both design and aesthetics, and can be easily obtained in any shape A translucent zirconia sintered body and a method for producing the same are provided.

  As a result of intensive investigations on the relationship between the color tone and transparency of the colored translucent zirconia sintered body and the composition and structure of the sintered body, the present researchers increase the content of the colorant in the sintered body. It has been found that the transparency, particularly the linear transmittance, of the colored translucent zirconia sintered body is extremely lowered, so that it does not become a sintered body having both translucency and dark color tone.

  Further, a colored transmissive zirconia sintered body containing a lanthanoid rare earth element and titania and having a controlled content of lanthanoid rare earth element and titania and porosity is transparent. Was found to exhibit a clear color tone without lowering. In addition, a primary sintered body containing a lanthanoid rare earth element and titania and having no pores inside the crystal grains (hereinafter referred to as intragranular pores) is produced, and then the titania in the primary sintered body is sufficiently obtained. It has been found that a colored translucent zirconia sintered body having a clear color tone can be obtained without reducing transparency by performing a hot isostatic pressing process while reducing.

  That is, the present invention is characterized by containing yttria in an amount of 6 mol% to 15 mol%, titania in an amount of 3 mol% to 20 mol%, an lanthanoid rare earth element in an oxide equivalent of at least 4 mol%, and a porosity of at most 1000 ppm. A colored translucent zirconia sintered body.

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

The zirconia sintered body of the present invention is a colored translucent zirconia sintered body, is a zirconia polycrystalline body having a color tone other than colorless and having translucency. Therefore, the colored translucent zirconia sintered body of the present invention includes a colorless translucent zirconia sintered body (hereinafter referred to as transparent zirconia sintered body), an opaque zirconia sintered body that does not transmit light (hereinafter referred to as opaque zirconia sintered body). ) And zirconia single crystals. The transparent zirconia sintered body here has a maximum linear transmittance of 10% or more at a sample thickness of 1 mm at a measurement wavelength of 400 nm to 800 nm, for example, −3 ≦ a ^* ≦ 3 and −3 ≦ b ^* ≦ 3. It is a sintered body satisfying

  The colored translucent zirconia sintered body of the present invention contains 6 mol% to 15 mol%, preferably 8 mol% to 12 mol%, of yttria with respect to zirconia. When the yttria content is within this range, the crystal phase tends to have a cubic fluorite structure. Thereby, a colored translucent zirconia sintered compact shows high transparency.

  If the yttria content is less than 6 mol% or the yttria content exceeds 15 mol%, crystal phases other than cubic crystals tend to be mixed, and the transparency of the sintered body is lowered.

The colored translucent zirconia sintered body of the present invention contains 3 to 20 mol% of titania, and preferably contains 8 to 15 mol% of titania. When the sintered body contains titania in this range, the transparency of the sintered body is increased. On the other hand, when the titania content of the sintered body is less than 3 mol%, the transparency of the sintered body is lowered. On the other hand, when the titania content exceeds 20 mol%, a compound of a pyrochlore type oxide (ZrTiO ₄ or the like) is generated in the sintered body, so that the transparency is easily lowered.

  The content of titania is mol% with respect to the total amount of zirconia and yttria in the colored translucent zirconia sintered body.

The colored translucent zirconia sintered body of the present invention contains at least 4 mol% of a lanthanoid rare earth element in terms of oxide. The content of the lanthanoid rare earth element is preferably at least 4.5 mol%, more preferably at least 5 mol% in terms of oxide. When the lanthanoid rare earth element contained in the sintered body is less than 4 mol% in terms of oxide, the color tone of the sintered body becomes weak, and in particular, the value of the lightness L ^* becomes too large.

When the lanthanoid rare earth element contained in the sintered body is increased, the value of the lightness L ^* is lowered and a deeper color tone can be obtained. However, if the lanthanoid rare earth element is too much, a pyrochlore oxide is generated in the sintered body, and the translucency of the sintered body tends to be lowered. Therefore, the lanthanoid rare earth element contained in the colored translucent zirconia sintered body of the present invention is preferably at most 30 mol% in terms of oxide, more preferably at most 25 mol%, and at most 20 mol. % Is more preferable, and at most 15 mol% is particularly preferable.

  The content of the lanthanoid rare earth element is mol% with respect to the total amount of zirconia, yttria and titania in the colored translucent zirconia sintered body.

  The lanthanoid rare earth element contained in the colored translucent zirconia sintered body of the present invention is at least one of praseodymium (Pr), neodymium (Nd), erbium (Er), gadolinium (Gd), and holonium (Ho). And any one or more of praseodymium (Pr), neodymium (Nd) or erbium (Er) is preferable, and one or more of praseodymium (Pr) or neodymium (Nd) is more preferable. When the sintered body contains these lanthanoid-based rare earth elements, the sintered body has a deep color tone while maintaining high transparency. Further, by containing praseodymium (Pr) or neodymium (Nd), it becomes easy to obtain a sintered body having a particularly deep color tone while maintaining transparency.

  In the colored translucent zirconia sintered body of the present invention, it is preferable that yttria, titania and a lanthanoid rare earth element are dissolved in zirconia.

  The colored translucent zirconia sintered body of the present invention preferably contains no fluorine. When elemental fluorine or a fluorine-containing compound is included, the transparency of the sintered body tends to be low. Since fluorine affects the sinterability, it is considered that fluorine suppresses pore elimination during the sintering process, and many pores remain in the sintered body. Therefore, the colored translucent zirconia sintered body of the present invention is preferably less than 0.5% by weight based on the weight of the sintered body with fluorine as a fluorinated material, and preferably substantially free of fluorinated material. .

  The colored translucent zirconia sintered body of the present invention has a high porosity of 1000 ppm (0.1% by volume).

  The inventors have found that the transparency of the zirconia sintered body is caused by residual pores, and clarified the correlation between the transparency and the amount of residual pores using a light scattering model based on Mie scattering. According to this, the translucent zirconia sintered body has a correlation between the linear transmittance and the porosity at the same measurement wavelength (J. Am. Ceram. Soc, 91 [3] p813-818 (2008). )). As a result of further studies, the present inventors have found that the same correlation as described above exists between the maximum linear transmittance and the porosity in the colored translucent zirconia sintered body.

  Here, in the present invention, the porosity is a ratio (volume%) of residual pores to the volume of the colored translucent zirconia sintered body.

  The porosity V of the colored translucent zirconia sintered body of the present invention is at most 1000 ppm (0.01 vol%), preferably at most 850 ppm (0.085 vol%), preferably 500 ppm ( 0.05 vol%) is more preferred, 250 ppm (0.025 vol%) is more preferred, and at most 200 ppm (0.02 vol%) is preferred. When the porosity V exceeds 1000 ppm, the transparency is lowered. Furthermore, when the porosity V is at most 250 ppm, the maximum linear transmittance increases to 35% or more.

  In particular, when a colored translucent zirconia sintered body having a high maximum linear transmittance is used, the porosity V is preferably at most 100 ppm (0.01% by volume), and at most 50 ppm (0.005% by volume). More preferably. When the porosity V is at most 100 ppm, the maximum linear transmittance is as high as 60% or more.

  On the other hand, the lower the porosity V, the higher the transparency, and it is preferable that the porosity is not substantially included. Therefore, although there is no lower limit value of the porosity V, even if the porosity is at least 1 ppm, preferably at least 10 ppm, the sintered body having the transparency intended by the present invention is obtained.

  The porosity in this invention can be calculated | required by the following (1) Formula.

V = 100 × (4 · r · C) / (3 · Q) (1)
(Where V: porosity (% by volume), C: scattering coefficient (1 / m), r: residual pore radius (m), Q: scattering efficiency (−), and r = 5 × 10 ⁻⁸ m is there.)

  Note that the scattering coefficient C in the equation (1) is a value obtained by the following equation (2).

C = − (1 / t) · Ln {(T / 100) / (1-R) ² } (2)
(Where C: scattering coefficient (1 / m), T: maximum linear transmittance (%) of sintered body, R: reflectance (−), t: sample thickness (m), R = 0.14 Is)

The value of the scattering efficiency Q varies depending on the measurement wavelength λ for measuring the linear transmittance. Therefore, when obtaining the porosity V in the equation (1), it is necessary to use the scattering coefficient Q having the same λ as the measurement wavelength λ in which the maximum linear transmittance T of the sintered body in the equation (2) is measured. is there. The measurement wavelength λ and the scattering efficiency Q can be approximately obtained using the following equation (3).
Q = 5.010-2.370e− ² · λ + 4.813e ⁻⁵ · λ ²
−5.032e ⁻⁸ · λ ³ + 2.638e ⁻¹¹ · λ ⁴ −5.535e ⁻¹⁵ · λ ⁵ (3)
(However, λ: Measurement wavelength when the maximum linear transmittance is measured (nm))

  In the colored translucent zirconia sintered body of the present invention, the maximum linear transmittance at a sample thickness of 1 mm and a measurement wavelength of 300 nm to 800 nm is preferably at least 10%, more preferably 35%, and at least 40%. More preferably, it is preferably at least 50%, more preferably at least 60%. A sintered body having a maximum linear transmittance of at least 10% has high transparency and tends to have high aesthetics.

  The colored translucent zirconia sintered body of the present invention preferably has a maximum total light transmittance at a sample thickness of 1 mm and a measurement wavelength of 300 nm to 800 nm of at least 40%, more preferably at least 50%. More preferably, it is at least 60%. A sintered body having a maximum total light transmittance of at least 40% tends to have high translucency.

  Note that the linear transmittance and the total light transmittance are values having the relationship of the formula (4).

Ti = Tt−Td (4)
Tt: Total light transmittance (%)
Td: diffuse transmittance (%)
Ti: Linear transmittance (%)

  The colored translucent zirconia sintered body of the present invention preferably has a haze ratio of at most 75% at a sample thickness of 1 mm, more preferably at most 50%, and at most 40%. More preferably, at most 30% is particularly preferable. When the haze ratio at the sample thickness of 1 mm is at most 75%, the colored translucent zirconia sintered body becomes more transparent.

  The haze ratio H (%) can be obtained from the equation (5).

H = 100 × Td / Tt (5)
H: Haze rate (%)
Tt: Total light transmittance (%)
Td: diffuse transmittance (%)

The color tone of the colored translucent zirconia sintered body of the present invention 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. Furthermore, the color tone in the colored translucent zirconia sintered body of the present invention can be obtained by reflecting the light transmitted through the sintered body with a white plate and measuring the light transmitted through the sintered body again. Therefore, the color tone changes as the transparency of the sintered body changes. For example, when the maximum linear transmittance increases, the lightness L ^* and the hues a ^* and b ^* tend to increase. On the other hand, when the maximum linear transmittance decreases, the lightness L ^* and the hues a ^* and b ^* tend to decrease. In particular, the hues a ^* and b ^* are susceptible to transparency.

As described above, the color tone in the present invention is different from the color tone of the opaque zirconia sintered body having no translucency, that is, the lightness L ^* , hue a ^* , b ^* obtained from the reflected light on the surface of the sintered body. Value.

In the colored translucent zirconia sintered body of the present invention, the lightness L ^* at a sample thickness of 1 mm is preferably at most 70, the lightness L ^* is more preferably at most 60, and at most 55. More preferably. Further, when L ^* is in this range, the sintered body tends to have a deeper color tone. Further, the lightness L ^* is more preferably at least 5, and further preferably at least 35. When the lightness L ^* is at least 5, the hue tends to be clear.

The hues a ^* and b ^* of the colored translucent zirconia sintered body of the present invention greatly affect the hue. The hue a ^* indicates a color tone from red to green. The larger the a ^* value, the stronger the red, and the smaller the value, the stronger the green. On the other hand, the hue b ^* indicates blue shades from yellow, yellow becomes stronger as the b ^* value is large, the blue is stronger as b ^* value is smaller.

The hues a ^* and b ^* of the colored translucent zirconia sintered body of the present invention are not determined unconditionally because they greatly change when the translucency of the sintered body changes. For example, when the colored translucent zirconia sintered body of the present invention is blue, the hues a ^* and b ^* when the sample thickness is 1 mm are 10 ≦ a ^* ≦ 30 and −30 ≦ b ^* when the sample thickness is 1 mm ^. It is mentioned that it is ≦ -15.

Similarly, when the colored translucent zirconia sintered body exhibits a green color, the hues a ^* and b ^* when the sample thickness is 1 mm are −15 ≦ a ^* ≦ 0 and 70 ≦ b ^* ≦ 85. Can be mentioned. When the colored translucent zirconia sintered body exhibits a yellow color, the hues a ^* and b ^* when the sample thickness is 1 mm are −15 ≦ a ^* ≦ 0 and 85 <b ^* .

  The crystal phase of the colored translucent zirconia sintered body of the present invention is preferably a cubic crystal, more preferably a cubic fluorite structure, and a single phase of a cubic fluorite structure. Further preferred. Since cubic crystals have no optical anisotropy, there is no birefringence at the polycrystalline interface. Therefore, since the crystal phase of the sintered body is a cubic single phase, the sintered body tends to have particularly high transparency.

  The average crystal grain size of the colored translucent zirconia sintered body of the present invention is preferably at most 60 μm, more preferably at most 50 μm, further preferably at most 45 μm, and at most 40 μm. It is particularly preferred that By setting the average crystal grain size of the sintered body to 50 μm at most, mechanical strength, particularly bending strength is improved.

  The colored translucent zirconia sintered body of the present invention preferably has an average three-point bending strength of at least 100 MPa, more preferably at least 150 MPa, and further preferably at least 200 MPa. If the average bending strength is low at 100 MPa, it becomes difficult to break when used in applications such as exterior members.

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

  The colored translucent zirconia sintered body of the present invention is formed by molding a zirconia powder containing yttria, titania and a lanthanoid rare earth element, followed by normal pressure sintering, and further performing hot isostatic pressing (HIP) treatment and annealing. This is a production method, and it can be obtained by subjecting a primary sintered body having a relative density of 90% to 98% and an average crystal grain size of at most 10 μm to HIP treatment.

  The zirconia powder (hereinafter referred to as raw material powder) containing yttria, titania and lanthanoid rare earth elements used in the production method of the present invention is not particularly limited as long as it contains a predetermined amount of yttria, titania and lanthanoid rare earth elements. The amount of yttria, titania, and lanthanoid rare earth element in the raw material powder may be the same as the composition of the target colored translucent zirconia sintered body.

  From an industrial viewpoint, it is preferable to use a mixed powder obtained by mixing yttria solid solution zirconia powder, titania powder and lanthanoid rare earth element oxide powder as the raw material powder.

Yttria solid solution of zirconia powder used in the powder mixture, 99.9% purity, it is preferable to use a powder having a specific surface area of ^{3m 2} / ^g~20m 2 / g. Furthermore, the yttria solid solution zirconia powder is preferably a powder having an average crystallite diameter of 10 nm to 50 nm and an average secondary particle diameter of 100 nm to 500 nm, and a powder produced by a wet synthesis method such as a hydrolysis method is particularly preferable. .

Titania powder used in the powder mixture purity titania 99.9% or more, preferably a specific surface area of ^{10m 2} / ^g~100m 2 / g, a purity of titania 99.95% or more, the average crystallite diameter More preferably, it is a fine powder of 30 nm or less and an average secondary particle diameter of 500 nm or less.

  The lanthanoid rare earth element oxide powder used as the mixed powder preferably has a lanthanoid rare earth element oxide purity of 99% or more.

  In the case of mixing these powders, the method is not particularly limited as long as both are uniformly dispersed, but wet mixing such as a wet ball mill and a wet stirring mill can be mixed more preferably.

  In the production method of the present invention, a raw material powder is molded to obtain a molded body to be subjected to atmospheric pressure sintering (hereinafter referred to as primary sintering).

  The raw material powder molding method is not limited as long as it can obtain a molded body having a shape suitable for primary sintering, and is generally used for ceramic molding, such as press molding and cold isostatic pressing. A molding method such as cast molding, extrusion molding, and injection molding can be used.

  In the production method of the present invention, a primary sintered body to be subjected to HIP treatment by primary sintering of the molded body is produced. The relative density of the primary sintered body is not less than 90% and not more than 98%, and the average crystal grain size is at most 10 μm. The relative density of the primary sintered body is preferably 91% or more, and more preferably 92% or more. The relative density of the primary sintered body is preferably 97% or less, and more preferably 95% or less. When the relative density of the primary sintered body is less than 90% or exceeds 98%, pore elimination by the HIP treatment does not proceed sufficiently, and the transparency of the resulting colored translucent zirconia sintered body decreases.

  The translucency of the colored translucent zirconia sintered body of the present invention strongly depends on the primary sintered body structure. Therefore, when the average crystal grain size of the primary sintered body exceeds 10 μm, the intragranular pores are likely to remain in the primary sintered body, and the pores are not easily excluded even after the HIP treatment. On the other hand, when the average crystal grain size is at most 10 μm, pores in the primary sintered body exist at the grain boundaries. This facilitates pore removal by HIP processing. Further, when the average grain size of the primary sintered body is at most 10 μm, plastic flow of the crystal grains easily occurs during the HIP process. Thereby, it is considered that pore removal during HIP processing becomes efficient. The average crystal grain size of the primary sintered body is preferably at most 5 μm, more preferably at most 4 μm, and further preferably at most 3.5 μm. Thereby, pore elimination is easily promoted. Although the lower limit of the average crystal grain size of the primary sintered body is not particularly limited, for example, it can be raised to at least 0.5 μm.

  Lanthanoid rare earth elements have an effect of promoting the growth of crystal grains. Therefore, it is difficult to obtain a fine primary sintered body by adding only the lanthanoid rare earth element or its oxide to the zirconia powder. However, co-addition of titania and a lanthanoid rare earth element facilitates refinement of the structure of the primary sintered body.

  In the production method of the present invention, primary sintering is performed by atmospheric pressure sintering. The primary sintering conditions are not particularly limited as long as a primary sintered body having the above relative density and average crystal grain size is obtained. In particular, the primary sintering temperature varies depending on the composition of the objective colored translucent zirconia sintered body, the type and content of the lanthanoid rare earth element, and the like. Therefore, the primary sintering temperature can be appropriately changed according to the composition of the objective colored translucent zirconia sintered body, the type and content of the lanthanoid rare earth element. When praseodymium is used as the lanthanoid rare earth oxide, the primary sintering temperature may be 1250 ° C. or higher and 1500 ° C. or lower, and the more preferable primary sintering temperature may be 1300 ° C. or higher and 1450 ° C. or lower. Examples of the primary sintering temperature include 1325 ° C. or higher and 1400 ° C. or lower.

  Primary sintering can be performed in an atmosphere such as air, oxygen, or vacuum, but is most preferably performed in air.

  In the manufacturing method of the present invention, the primary sintered body is subjected to HIP treatment.

  The HIP treatment is preferably at a HIP treatment temperature higher than the primary sintering temperature. When the HIP processing temperature is higher than the primary sintering temperature, the elimination of residual pores in the primary sintered body is easily promoted. Moreover, it is preferable that HIP processing temperature is 1400 degreeC or more and less than 1800 degreeC, and it is more preferable that it is 1450 degreeC or more and 1550 degrees C or less. By setting the HIP treatment temperature to 1400 ° C. or higher, pore removal of the sintered body is further promoted, and the translucency of the obtained sintered body is improved. On the other hand, when the HIP processing temperature is less than 1800 ° C., abnormal grain growth of the sintered body crystal grains is suppressed, and the strength tends to increase.

  The HIP treatment time is preferably at least 1 hour. By setting the HIP treatment for at least one hour, the elimination of pores from the sintered body during the HIP treatment is easily promoted.

  The pressure medium for the HIP process is not particularly limited as long as it is a non-oxidizing atmosphere. Examples of the pressure medium include nitrogen gas and argon gas, and argon gas is preferable.

  The pressure of the HIP treatment is preferably at least 50 MPa, more preferably 100 MPa or more and 200 MPa or less. When the pressure of the HIP process is at least 50 MPa, pore removal during the HIP process tends to be efficient. Further, by setting the pressure to 100 MPa or more, pore elimination is further promoted, and the transparency of the obtained sintered body tends to be high.

In the HIP treatment, it is preferable to reduce titanium in the sintered body. Thereby, translucency tends to be high. The reduction of titanium means that tetravalent Ti in titania (TiO ₂ ) is reduced to trivalent Ti (TiO _1.5 ). By promoting the reduction of titanium, oxygen vacancies are formed and the movement (disappearance) of the pores is promoted.

  In the production method of the present invention, the container in which the sample is placed by the HIP process is preferably a container made of a reducing material. An example of the reducing material is carbon. Thereby, the reduction | restoration of titanium is easy to be accelerated | stimulated.

  In the manufacturing method of the present invention, the HIP-treated body after the HIP treatment is annealed. The HIP-treated body after the HIP treatment exhibits a dark black color due to the reduction of titanium, but can be made into a transparent colored translucent zirconia sintered body by annealing treatment.

  The annealing treatment is preferably held at a temperature of 800 ° C. to 1200 ° C. for 1 hour or more at normal pressure in an oxidizing atmosphere. Examples of the oxidizing atmosphere include air or oxygen, and it is easy to carry out in the air.

  The colored translucent zirconia sintered body of the present invention is a zirconia polycrystal having both high translucency and a dark color tone. Even when the colored translucent zirconia sintered body of the present invention is a fine part, it can be a part having a clear coloration.

The figure which shows the linear transmittance | permeability of the colored translucent zirconia sintered compact of Examples 1-4. The figure which shows the linear transmittance | permeability of the colored translucent zirconia sintered compact of Comparative Examples 1-4 Structure chart of colored translucent zirconia sintered body of Example 3 (scale in the figure is 30 μm) XRD diagrams of colored translucent zirconia sintered bodies of Examples 1 to 4 The figure which shows the relationship between the porosity V and the maximum linear transmittance

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

(Haze rate)
The sintered body of the example or the comparative example was processed into a sample thickness of 1 mm and subjected to double-side mirror polishing to a surface roughness Ra = 0.02 μm or less as a measurement sample. The haze ratio was measured using a haze meter (Nippon Denshoku Co., Ltd., NDH5000) in accordance with JIS K7105 “Plastic Optical Properties Test Method” and JIS K7136 “Plastic—How to Obtain Haze of Transparent Materials”. The light source used was D65 light.

(Total light transmittance and linear transmittance)
The linear transmittance was measured with a double beam type spectrophotometer (manufactured by JASCO Corporation, model V-650). The measurement sample was the same as that used for haze rate measurement. Using a deuterium lamp and a halogen lamp as a light source, the measurement wavelength of 300 nm to 800 nm was scanned, and the linear transmittance at each wavelength was measured.

(Average crystal grain size)
The measurement sample was surface ground and then mirror polished using diamond abrasive grains of 9 μm, 6 μm and 1 μm. After the polished surface was thermally etched, SEM observation was performed.

  The thermal etching was performed by placing the sample in an electric furnace and holding the sample at a temperature 50 ° C. to 100 ° C. lower than the HIP processing temperature of the sample for 2 hours. From the SEM picture, the average particle size Am. Ceram. Soc. , 52 [8] 443-6 (1969).

D = 1.56L (6)
Here, D: average crystal grain size (μm), L: average length (μm) of crystal grains crossing an arbitrary straight line. The value of L was an average value of 100 or more measured lengths.

(Lightness, hue)
As a measurement sample, a sample whose thickness was processed to 1 mm and mirror-polished to a surface roughness Ra = 0.02 μm or less was used. The measurement was carried out using a precision spectrophotometric colorimeter (TC-1500SX, manufactured by Tokyo Denshoku Co., Ltd.) according to Sections 5.3 and 5.4 of JIS K7105 “Plastic Optical Properties Test Method”. In the measurement, the D65 light beam is applied to a measurement sample having a regular standard white plate on the back surface, the light transmitted through the measurement sample is reflected by the white plate, the light transmitted through the measurement sample is measured again, and the lightness L ^* , Hue a ^* and b ^* were determined. For the measurement, D65 light was used.

Example 1
(Preparation of raw material powder)
A mixed powder of zirconia powder, titania powder and praseodymium oxide (PrO _11/6 ) powder was used as the raw material powder.

  First, 10 mol% titania was added to the total amount of yttria and zirconia in the 10 mol% yttria-stabilized zirconia powder. Thereafter, 5 mol% of praseodymium oxide powder was added to the total amount of yttria, zirconia and titania in the yttria-stabilized zirconia powder and titania powder to prepare a mixed powder.

  As the 10 mol% yttria-stabilized zirconia powder, a hydrolyzed method (TZ-10YS, manufactured by Tosoh Corporation) was used. Further, as the titania powder, high-purity titania powder (F-4, manufactured by Super Titania) manufactured by a gas phase method was used, and SU-FP (manufactured by Shin-Etsu Chemical) was used as the praseodymium oxide powder.

  These powders were mixed in a ball mill for 72 hours using a zirconia φ10 mm ball in an ethanol solvent, and dried to obtain a raw material powder.

(Preparation of primary sintered body)
The raw material powder was molded at a pressure of 50 MPa by a die press and then further molded 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 2 mm.

  The obtained cylindrical molded body was primarily sintered to obtain a primary sintered body (sample number: No. 1-1). The primary sintering conditions were an atmospheric temperature, a heating rate of 100 ° C./hour, a primary sintering temperature of 1350 ° C., and a primary sintering time of 2 hours.

  Table 1 shows the raw material powder, the primary sintering conditions, and the results of the primary sintered body.

(Preparation of colored translucent zirconia sintered body)
The obtained primary sintered body was subjected to HIP treatment to obtain a HIP-treated body. The HIP treatment conditions were a temperature of 1500 ° C., a pressure of 150 MPa, and a holding time of 1 hour. Note that argon gas having a purity of 99.9% was used as the pressure medium, and the sample was placed in a carbon container.

  The obtained HIP-treated body was annealed. The annealing conditions were 1000 ° C. and 1 hour in the air. The HIP-treated body after the HIP treatment was black, but the colored translucent zirconia sintered body after the annealing treatment was translucent and had a deep yellow color.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase. The results of the colored translucent zirconia sintered body after annealing are shown in Table 2.

Example 2
A primary sintered body (sample number: No. 1) was molded and primary sintered in the same manner as in Example 1 except that the amount of praseodymium oxide powder added was 10.0 mol% and the primary sintering temperature was 1400 ° C. 1-2) was obtained. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 1 to obtain a colored translucent zirconia sintered body of Example 2.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 1 shows the results of the raw material powder, the primary sintering conditions and the primary sintered body, and Table 2 shows the results of the obtained colored translucent zirconia sintered body.

Example 3
Molding and primary sintering were performed in the same manner as in Example 1 except that neodymium oxide (NdO _1.5 ) powder (manufactured by Shin-Etsu Chemical Co., Ltd., neodymium purity 99.9%) was used instead of praseodymium oxide powder. A ligation (sample number: No. 1-3) was obtained. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 1 to obtain a colored translucent zirconia sintered body of Example 3.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 1 shows the results of the raw material powder, the primary sintering conditions and the primary sintered body, and Table 2 shows the results of the obtained colored translucent zirconia sintered body.

Example 4
A primary sintered body (sample number: No. 1-4) was obtained by molding and primary sintering in the same manner as in Example 2 except that neodymium oxide powder was used instead of praseodymium oxide powder. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 2 to obtain a colored translucent zirconia sintered body of Example 4.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 1 shows the results of the raw material powder, the primary sintering conditions and the primary sintered body, and Table 2 shows the results of the obtained colored translucent zirconia sintered body.

Example 5
A primary sintered body (sample number: No. 1) was molded and primary sintered in the same manner as in Example 1 except that neodymium oxide powder was used instead of praseodymium oxide powder, and the addition amount was 25 mol%. -5) was obtained. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 2 to obtain a colored translucent zirconia sintered body of Example 4.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method.

  Table 1 shows the results of the raw material powder, the primary sintering conditions and the primary sintered body, and Table 2 shows the results of the obtained colored translucent zirconia sintered body.

Example 6
A primary sintered body (sample number: No. 1-6) was obtained by molding and primary sintering in the same manner as in Example 2 except that erbium oxide powder was used instead of praseodymium oxide powder. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 2 to obtain a colored translucent zirconia sintered body of Example 4.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 1 shows the results of the raw material powder, the primary sintering conditions and the primary sintered body, and Table 2 shows the results of the obtained colored translucent zirconia sintered body.

  The linear transmittances of Examples 1, 2, 3, and 4 are shown in FIG. All showed high linear transmittance. Furthermore, it was found that a specific wavelength was absorbed and colored due to the presence of the lanthanoid rare earth element.

  The XRD profiles of Examples 1, 2, 3, and 4 are shown in FIG. All had a cubic fluorite structure.

  The colored translucent zirconia sintered bodies of Examples 1 to 4 were composed of homogeneous fine crystal particles. The result of SEM observation of the colored translucent zirconia sintered body of Example 3 is shown in FIG.

Comparative Example 1
A primary sintered body (sample number: No. 2-1) was obtained by molding and primary sintering in the same manner as in Example 1 except that the amount of praseodymium oxide powder was 1.0 mol%. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 1 to obtain a colored translucent zirconia sintered body of Comparative Example 1.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 3 shows the results of the raw material powder, the primary sintering conditions, and the primary sintered body, and Table 4 shows the results of the obtained colored translucent zirconia sintered body.

Comparative Example 2
A primary sintered body (sample number: No. 2-2) was obtained by molding and primary sintering in the same manner as in Example 1 except that the amount of praseodymium oxide powder was 2.0 mol%. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Example 1 to obtain a colored translucent zirconia sintered body of Comparative Example 2.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 3 shows the results of the raw material powder, the primary sintering conditions, and the primary sintered body, and Table 4 shows the results of the obtained colored translucent zirconia sintered body.

Comparative Example 3
A primary sintered body (sample number: No. 2-3) was obtained by molding and primary sintering in the same manner as in Comparative Example 1 except that neodymium oxide powder was used instead of praseodymium oxide powder. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Comparative Example 1 to obtain a colored translucent zirconia sintered body of Comparative Example 3.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 3 shows the results of the raw material powder, the primary sintering conditions, and the primary sintered body, and Table 4 shows the results of the obtained colored translucent zirconia sintered body.

Comparative Example 4
A primary sintered body (sample number: No. 2-4) was obtained by molding and primary sintering in the same manner as in Comparative Example 2 except that neodymium oxide powder was used instead of praseodymium oxide powder. The obtained primary sintered body was subjected to the same HIP treatment and annealing treatment as in Comparative Example 2 to obtain a colored translucent zirconia sintered body of Comparative Example 4.

  The obtained colored translucent zirconia sintered body had the same composition as the raw material powder, and its density was 100% within the measurement error range of the Archimedes method. The crystal phase was a fluorite cubic single phase.

  Table 3 shows the results of the raw material powder, the primary sintering conditions, and the primary sintered body, and Table 4 shows the results of the obtained colored translucent zirconia sintered body.

From Comparative Examples 1 to 4, it was confirmed that when the amount of lanthanoid added was small, the color tone was thinner than that of the sintered body of the example. Further, these sintered bodies had particularly high L ^* .

Comparative Example 5
The firing of Comparative Example 5 was performed under the same conditions as in Example 6, except that yttria was 10.0 mol%, titania was 15.0 mol%, erbium oxide was 5 mol%, and the relative density of the primary sintered body was 98.1%. A ligature was obtained. The results are shown in Table 4.

  The porosity of the obtained sintered body exceeded 1000 ppm. The sintered body obtained by subjecting the primary sintered body having a relative density exceeding 98% to HIP treatment had many residual pores and the transparency was extremely low.

Reference example 1
A primary sintered body (sample number: No. 3-1) was obtained by molding and primary sintering in the same manner as in Example 1 except that no lanthanoid rare earth oxide was used. The obtained primary sintered body was subjected to HIP treatment in the same manner as in Example 1 to obtain a HIP-treated body. Since the obtained HIP-processed body was transparent, annealing treatment was not performed, and the transparent zirconia sintered body of Reference Example 1 was obtained. The results are shown in Table 5.

The obtained transparent zirconia sintered body had high linear transmittance and high transparency. However, the hue was in the range of −3 ≦ a ^* ≦ 3 and −3 ≦ b ^* ≦ 3 and was colorless.

Reference example 2
As the zirconia powder, 8 mol% yttria-containing zirconia powder (manufactured by Tosoh, TZ-8Y) produced by a hydrolysis method was used, and a mixed powder to which 5 mol% of neodymium oxide was added was used as a raw material powder. In addition, titania powder was not used for the raw material powder of Reference Example 2.

  A colored translucent zirconia sintered body was produced under the same conditions as in Example 1 except that the raw powder was used, the primary sintering temperature was 1450 ° C., the HIP treatment temperature was 1500 ° C., and the annealing treatment was not performed. .

  Table 6 shows the results of the obtained colored translucent zirconia sintered body.

  The sintered body of Reference Example 2 that did not contain titania was an opaque zirconia sintered body having a very low linear transmittance and exhibiting a blue color.

  The colored translucent zirconia sintered body of the present invention has a highly transparent and dark color tone. Therefore, it can be suitably used as various small and thin members including exterior members such as electronic devices, in addition to ornaments, jewelry and crafts.

Claims (7)

It is characterized in that it contains 6 mol% or more and 15 mol% or less of yttria, 3 mol% or more and 20 mol% or less of titania, at least 4 mol% of lanthanoid rare earth element in terms of oxide , does not contain fluorine, and has a high porosity of 1000 ppm. Colored translucent zirconia sintered body. 2. The colored translucent zirconia sintered body according to claim 1, wherein the average crystal grain size is at most 60 μm. The colored translucent zirconia sintered body according to any one of claims 1 to 3, wherein the lanthanoid rare earth element is at least one of praseodymium, neodymium, and erbium. The colored translucent zirconia sintered body according to any one of claims 1 to 4, wherein a lightness L ^* at a sample thickness of 1 mm is at most 70. A manufacturing method in which a zirconia powder containing yttria, titania and a lanthanoid rare earth element is molded, sintered at normal pressure, and then subjected to hot isostatic pressing (HIP) treatment and annealing, and the relative density is 90% or more and 98. The method for producing a colored translucent zirconia sintered body according to any one of claims 1 to 5, wherein a primary sintered body having an average crystal grain size of at most 10 µm is subjected to HIP treatment. The method for producing a colored translucent zirconia sintered body according to claim 6, wherein the HIP treatment is performed at a HIP treatment temperature higher than a primary sintering temperature. A member using the colored translucent zirconia sintered body according to any one of claims 1 to 5.

Images