JP6626705B2 - Color ceramics - Google Patents

Description

  The present invention relates to a color ceramic.

  Zirconia-based sintered bodies have high mechanical properties and can provide a sense of quality and aesthetic satisfaction. Therefore, in recent years, they have been suitably used as decorative parts such as watch bezels, mobile phone keys, and pillows. . Various studies have been made on coloring components in order to provide various colors in response to diversification of tastes.

The applicants of the present application have proposed that as a pale blue (hereinafter, referred to as light blue) color ceramic, zirconia containing a stabilizer is used as a main component, and alumina (Al ₂ O ₃ ) and nickel spinel (NiAl ₂ O) are used. ₄ ), and a pale blue (hereinafter, referred to as light blue) color ceramics has been proposed. (See Patent Document 1)

International Publication No. 2007/108416

  In recent years, there has been a demand for a reduction in color variation in order to provide consumers with high aesthetic satisfaction.

  The present invention has been devised in order to solve the above-mentioned demands, and an object of the present invention is to provide a color ceramic which can provide a user with high aesthetic satisfaction by reducing color variation.

The color ceramic of the present invention contains zirconia crystals and alumina crystals, is mainly composed of zirconia containing a stabilizer, and has a content of Al in terms of Al ₂ O ₃ of 15% by mass or more and 25% by mass or less. The content in terms of NiO is 0.5% by mass or more and 5% by mass or less, the maximum diameter of the alumina crystal is 1.2 μm or less, and the color tone is a lightness index in CIE1976L * a * b * color space. L * is 57 or more and 79 or less, chromaticness index a * is -16 or more and -5 or less, and chromaticness index b * is -22 or more and -2 or less .

  ADVANTAGE OF THE INVENTION According to the color ceramic of this invention, since a color variation is small, a high aesthetic satisfaction can be given to a consumer.

  Hereinafter, an example of the color ceramics of the present embodiment will be described.

The color ceramic of the present embodiment includes a zirconia crystal and an alumina crystal. The color ceramic of the present embodiment is mainly composed of zirconia containing a stabilizer, and has a content of 15% by mass or more and 25% by mass or less of Al in terms of Al ₂ O ₃ and a content of Ni in terms of NiO in terms of NiO. It contains 0.5% by mass or more and 5% by mass or less.

In the color ceramics of the present embodiment, the maximum diameter of the alumina crystal is 1.2 μm or less. By satisfying such a configuration, the color ceramic of the present embodiment exhibits a light blue color tone and has a small color variation, so that a high aesthetic satisfaction can be given to the consumer. In particular, the maximum diameter of the alumina crystal is preferably 1 μm or less.

  Note that the light ceramic color tone of the color ceramic of the present embodiment is defined as a lightness index L * in a CIE1976L * a * b * color space of 57 or more and 79 or less, a chromaticness index a * of -16 or more and -5 or less, The Kness index b * is −22 or more and −2 or less.

  Next, various measurement methods and confirmation methods will be described.

  First, the main component is a component exceeding 70% by mass of 100% by mass of all components constituting the color ceramic.

Regarding the content of each component, the contents of Zr, Al, and Ni were determined using a fluorescent X-ray analyzer (XRF) or an ICP emission spectrometer (ICP), and ZrO ₂ (zirconia), Al It can be obtained by converting into ₂ O ₃ and NiO.

  In addition, as a method for confirming the presence of the zirconia crystal and the alumina crystal, measurement may be performed by an X-ray diffractometer (XRD), and it may be confirmed by checking with JCPDS data.

The maximum diameter of the alumina crystal can be determined as follows. When the zirconia crystal and the alumina crystal are mirror-finished and observed using a scanning electron microscope (SEM) with the surface subjected to fire etching at a temperature 50 to 100 ° C. lower than the firing temperature as a measurement surface, the zirconia crystal turns white. It is easy to discriminate because the alumina crystal looks black because the particles are zirconia crystal and alumina crystal is confirmed by using an energy dispersive X-ray spectrometer (EDS) attached to the SEM. It can also be confirmed by confirming the contained components. In order to determine the maximum diameter of the alumina crystal, for example, a black crystal is obtained by using a photograph taken with a SEM at a magnification of 10,000 times (observation area: about 90 μm ² : vertical 8.1 μm × horizontal 11.2 μm). Fill in black, read this as image data, apply image analysis software "A image-kun" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.) and perform image analysis to confirm the maximum diameter of each crystal. Just fine. As the analysis conditions, for example, the brightness of the particles may be “dark”, the binarization method may be “manual”, the small figure removal may be “0.01 μm”, and the threshold may be “40”. In the present embodiment, the alumina crystals include crystals in which Ni is dissolved in solid form.

The stabilizing agent is for maintaining the zirconia crystal in a stable phase state (tetragonal or cubic), for example, yttrium oxide (Y ₂ O ₃ ), cerium oxide (CeO ₂ ), It is at least one selected from prosium (Dy ₂ O ₃ ), magnesium oxide (MgO), calcium oxide (CaO), and the like. Here, if the stabilizer is yttria, the ionic radius is close to that of zirconia, the degree of stabilization is high, and coarse crystals are not easily generated, so that the color ceramics can have excellent mechanical properties.

The proportion of monoclinic crystals in the zirconia crystal is preferably 0.5% or less. The proportion of the monoclinic in the zirconia crystal was measured using XRD, and the reflection peak intensities of the monoclinic (111) and (11-1) and the reflection peak intensities of the tetragonal and cubic (111) were determined. And can be calculated from the following equation. (Im (111) + Im (11-1) / (Im (111) + Im (11-1)
+ It (111) + Ic (111)) × 100, where the single crystal (111) is Im (111), the single crystal (11-1) is Im (11-1) and the tetragonal (111) is It. (111) and cubic (111) are represented as Ic (111).

The stabilizer can be confirmed to be contained by qualitative analysis by XRF or ICP or by EDS. The content of Y (yttrium) can be determined by calculating the Y content by XRF or ICP, such as Zr, Al or Ni, and converting it to Y ₂ O _3. .

  Next, for the color tone, a lightness index L in the CIE1976L * a * b * color space was measured using a colorimeter (formerly Minolta CR-221 or its successor) in accordance with JIS Z 8722-2000. The value of * and the values of the chromaticness indices a * and b * may be determined. The measurement was performed by setting the light source to CIE standard light source D65, setting the illumination light receiving method to condition a ((45-n) [45-0]), and setting the measurement diameter to 3 mm.

Regarding the color variation, measurement was performed at a plurality of places of the color ceramics, and the obtained L *, a *, and b * values were used to calculate ΔE = ((ΔL *) ² + (Δa *) ² + ( Δb *) ² ) The color variation can be determined by ^{１ ／} .

  The zirconia crystal and the alumina crystal in the present embodiment have, for example, an average crystal grain size of 0.25 μm to 0.5 μm. In such a case, the average crystal grain size of all the crystals present in the color ceramic is also 0.25 μm to 0.5 μm. When the average crystal grain size in such a range is satisfied, it has excellent mechanical properties.

  In the color ceramics of the present embodiment, it is preferable that the average crystal grain size of the alumina crystal is 0.3 μm or more and 0.45 μm or less, and the average distance between the centers of gravity is 0.85 μm or more and 1.0 μm or less. When such a configuration is satisfied, the color variation is further suppressed, and a higher aesthetic satisfaction can be given to the consumer.

  The average crystal grain size is calculated by applying a method called particle analysis of image analysis software "A image kun" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.) in the same manner as when the maximum diameter of the alumina crystal was obtained. It can be obtained by analysis. The average distance between the centers of gravity may be calculated by using a method called the distance between the centers of gravity in the image analysis. The analysis conditions in the centroid distance method may be the same as in the particle analysis.

  In addition, the color ceramic of the present embodiment has a three-point bending strength of 900 MPa or more, which is required in accordance with JIS R 1601-2008. Further, the Vickers hardness Hv is 13 GPa or more. If the Vickers hardness Hv is 13 GPa or more, even if the Vickers hardness Hv comes into contact with a substance having a high hardness such as dust made of glass or metal, it is not easily damaged. The Vickers hardness Hv of this surface can be measured in accordance with JIS R 1610-2003.

The color ceramic of the present embodiment has an apparent density of 5.3 g / cm ³ or more. When the value of the apparent density satisfies the above range, the number of open pores on the surface is reduced, so that shedding of crystal grains generated from the outline of the open pores is suppressed, and excellent mechanical strength is obtained. The apparent density may be determined in accordance with JIS R 1634-1998.

  Since the color ceramics of the present embodiment can provide aesthetic satisfaction to the user due to little color variation, watch parts such as a watch bezel and a watch band piece, various keys to be pressed, pillows , Parts for mobile phone such as exterior, parts for guiding fishing line such as guide ring for fishing line, parts for accessories such as brooch, necklace, earring, ring, tie pin, tie-tack, medal, button, floor, wall, ceiling It can be suitably used as a part for building materials such as a tile or door handle to be decorated, a part for kitchen parts such as spoons and forks, a decorative part for other home appliances, and a part for automobiles such as an emblem.

  When the color ceramic of the present embodiment is provided in a decorative article (including the case where the color ceramic is a decorative article), the arithmetic average roughness Ra on the decorative surface for which the consumer seeks the decorative value is 0.03 μm or less. Is preferred. The arithmetic average roughness Ra may be measured according to JIS B 0601-2001. For example, using a stylus type surface roughness meter, the measurement length is 5 mm, the cutoff value is 0.8 mm, the tip of the stylus has a radius of 2 μm, and the speed is 0.5 mm / sec. What is necessary is just to scan a stylus.

  Next, an example of a method for manufacturing the color ceramics of the present embodiment will be described.

  First, a stabilized zirconia powder having an average particle diameter of 0.25 μm or more and 0.55 μm or less is prepared as a main raw material powder. Here, the stabilized zirconia powder is specifically produced by a coprecipitation method by adding at least one stabilizer selected from yttrium oxide, cerium oxide, dysprosium oxide, magnesium oxide and calcium oxide. The zirconia content is 95 to 99 mol%, and the stabilizer is 1 to 5 mol%. The stabilized zirconia powder may contain about 2% by mass of hafnium oxide.

  Also, an aluminum oxide powder having an average particle diameter of 0.6 μm or less (alumina powder in Table 1) and a nickel oxide powder having an average particle diameter of 0.8 μm or more and 1.0 μm are prepared. And, of the total of 100 parts by mass of the stabilized zirconia powder, aluminum oxide powder, and nickel oxide powder, aluminum oxide powder is 15 to 25 parts by mass, nickel oxide is 0.5 to 5 parts by mass, and the remainder is Is weighed so as to be a stabilized zirconia powder.

The stabilized zirconia powder, aluminum oxide powder, and nickel oxide powder may contain a component that promotes the grain growth of alumina crystals. For example, the content in the sintered body is such that Si is converted into SiO ₂ or Mg. It is preferable that the total of the values obtained by converting MgO and Ca into CaO be in the range of 200 to 400 ppm.

  In order to make the average crystal grain size of the alumina crystal 0.3 μm or more and 0.45 μm or less, an average crystal grain size of 0.2 μm or more and 0.32 μm or less is used, or the average grain size is obtained by mixing and pulverization described below. The diameter may be 0.2 μm or more and 0.32 μm or less. Further, in order to make the average distance between the centers of gravity 0.85 μm or more and 1.0 μm or less, in the following mixed pulverization, the dispersant is added to the stabilized zirconia powder, aluminum oxide powder, and nickel oxide powder in a total amount of 100 parts by mass. What is necessary is just to add in 2 to 0.3 mass part.

  Next, the weighed powders and water as a solvent are mixed and pulverized in a vibration mill, a ball mill or the like. Here, it is preferable that the balls used for the mixing and pulverization are made of color ceramics prepared in advance by the same composition and the same manufacturing method.

  Next, a predetermined amount of polyvinyl alcohol is added as a binder to the mixed and pulverized slurry, and the mixture is sprayed and dried using a spray dryer to obtain granulated granules. Then, using the granules, a desired shape such as a disk, a flat plate, a columnar body, an annular body, or the like is formed by a desired forming method, for example, a dry pressing method, a cold isostatic pressing method, or the like.

  Further, if the product shape is complicated, a molded product may be obtained by a cast molding method or an injection molding method using a slurry obtained by adding a solvent, a binder, or the like to the mixed and pulverized slurry. Furthermore, it is also possible to obtain a molded body by performing cutting after forming into a block shape or a shape close to a product shape by various molding methods. Then, after the obtained molded body is degreased as necessary, it is fired at a temperature of 1350 ° C. or more and 1550 ° C. or less in an air atmosphere to obtain a sintered body.

  The arithmetic mean roughness Ra can be reduced to 0.03 μm or less by barrel polishing the obtained sintered body. The barrel polishing may be performed for about 24 hours by a wet centrifugal barrel polishing machine using a medium and green carborundum (GC). Alternatively, a small diamond paste having an average particle diameter of 1 μm or less may be supplied to a tin lapping machine to perform lapping.

  Hereinafter, examples of the present invention will be specifically described, but the present invention is not limited to these examples.

  First, a stabilized zirconia powder having an average particle diameter of 0.35 μm, produced by a coprecipitation method, having 97 mol% of zirconia and 3 mol% of yttrium oxide as a stabilizer was prepared as a main raw material powder. Further, an aluminum oxide powder having an average particle diameter shown in Table 1 and a nickel oxide powder having an average particle diameter of 0.9 μm were prepared.

Then, the stabilized zirconia powder, aluminum oxide powder, and nickel oxide powder were weighed such that the content in terms of Al ₂ O ₃ and the content in terms of NiO in the sintered body became the values shown in Table 1. Except for the content in terms of Al ₂ O ₃ and the content in terms of NiO, they are zirconia (zirconium oxide), yttrium oxide, hafnium oxide, and inevitable impurities.

  Next, the weighed powders, water as a solvent, and 0.1 parts by mass of a dispersant were put into a vibration mill, a ball mill, or the like, and mixed and pulverized.

  Next, a predetermined amount of polyvinyl alcohol was added as a binder to the mixed and pulverized slurry, and the mixture was sprayed and dried using a spray dryer to obtain granulated granules. Then, a disk-shaped molding was obtained by a dry pressure molding method using the granules.

  Then, after the obtained molded body was degreased as necessary, each sample was obtained by firing at a temperature of 1500 ° C. in an air atmosphere.

Then, the contents of Al and Ni were determined using ICP, and the contents were converted into Al ₂ O ₃ and NiO, respectively. In addition, the contents of Si, Mg, and Ca were determined, and the total converted to SiO ₂ , MgO, and CaO, respectively, is shown in Table 1 as the sum of the auxiliary components.

Next, each sample was mirror-finished and fire-etched at a temperature 50 ° C. lower than the firing temperature, and the surface to be measured was observed using a SEM. The crystal that appeared white by EDS was zirconia crystal, It was confirmed that the crystals that appeared in the system were alumina crystals. Then, using a photograph taken with an SEM at a magnification of 10,000 times (observation area: about 90 μm ² : vertical 8.1 μm × horizontal 11.2 μm), black crystals are painted black, and this is read as image data, and image analysis is performed. The maximum diameter of the alumina crystal was obtained by performing image analysis by applying a method called particle analysis of software "A-image" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.). The analysis conditions were as follows: the lightness of the particles was “dark”, the binarization method was “manual”, the small figure removal was “0.01 μm”, and the threshold was “40”.

Next, the value of the lightness index L * and the chromaticness index a in the CIE1976L * a * b * color space were measured using a colorimeter (formerly Minolta CR-221) in accordance with JIS Z 8722-2000. * And b * values were determined. The measurement was performed by setting the light source to CIE standard light source D65, setting the illumination light receiving method to condition a ((45-n) [45-0]), and setting the measurement diameter to 3 mm.

In addition, color variation was measured at five locations for each sample, and the obtained values of L *, a *, and b * were used to calculate ΔE = ((ΔL *) ² + (Δa *) ² + ( Δb *) ² ) The color variation was determined by ^{１ ／} , and the colors were ranked in ascending order of the value of ΔE. Table 1 shows the results.

  From Table 1, Sample No. Sample Nos. 2 and 3 are sample Nos. Color variation was smaller than 1. From this result, it was found that when the maximum diameter of the alumina crystal was 1.2 μm or less, the color variation was small, and it was found that a high aesthetic satisfaction was given to the consumer.

In addition, zirconia containing zirconia crystals and alumina crystals, and containing zirconia containing a stabilizer as a main component, the content of Al in terms of Al ₂ O ₃ is 15% by mass to 25% by mass, and the content of Ni in terms of NiO. In the range of 0.5% by mass or more and 5% by mass or less, various color ceramics having different configurations were prepared, and the color tone was confirmed. The lightness index L * in the CIE1976L * a * b * color space was 57 or more and 79 or less, The chromaticness index a * was −16 or more and −5 or less, and the chromaticness index b * was −22 or more and −2 or less.

  Next, the amount of the dispersant added was changed, and the sample No. 7 to sample no. A sample was prepared in which the mixing and pulverizing time was extended toward 4, and color variation was confirmed. In addition, except that the addition amount of the dispersant was set to the value shown in Table 2, the sample No. of Example 1 was used. A sample was prepared in the same manner as in Preparation Method 3. Sample No. 7 is sample No. This is the same sample as No. 3.

Then, each of the obtained samples was mirror-finished, and the surface that had been fire-etched at a temperature lower by 50 ° C. than the firing temperature was observed using a SEM as a measurement surface, and the crystals that appeared white by EDS were zirconia crystals. It was confirmed that the crystals which appeared blackish were alumina crystals. Then, using a photograph taken with an SEM at a magnification of 10,000 times (observation area 90 μm ² : vertical 8.1 μm × horizontal 11.2 μm), a black crystal is painted black, and this is read as image data, and image analysis software is used. The average crystal grain size of the alumina crystals was determined by performing image analysis by applying a method called “A image kun” (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.) called particle analysis. The analysis conditions were as follows: the lightness of the particles was “dark”, the binarization method was “manual”, the small figure removal was “0.01 μm”, and the threshold was “40”.

  In addition, the same image is used to analyze the image by applying a method called a center-of-gravity distance method of image analysis software “A image-kun” (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.), so that the average center-of-gravity of alumina crystals is The distance was determined. The analysis conditions were the same as those described above.

Further, in the same manner as in Example 1, the value of the lightness index L *, the value of the chromaticness index a *, the value of the chromaticness index b *, and ΔE were obtained, and ranking was performed in ascending order of the value of ΔE. Table 2 shows the results.

  From Table 2, it was found that the average distance between the centers of gravity is preferably 0.85 μm or more and 1.0 μm or less, and by being in this range, higher aesthetic satisfaction can be given to the consumer.

Claims (3)

Zirconia containing a zirconia crystal and an alumina crystal and containing a stabilizer is a main component, the content of Al in terms of Al ₂ O ₃ is 15% by mass or more and 25% by mass or less, and the content of Ni in terms of NiO is 0%. 0.5 mass% or more and 5 mass% or less, the maximum diameter of the circle equivalent diameter of the alumina crystal is 1.2 μm or less, and the color tone has a lightness index L * in a CIE1976L * a * b * color space of 57 or more and 79 or less. A color blue ceramic having a chromaticness index a * of -16 or more and -5 or less and a chromaticness index b * of -22 or more and -2 or less .   2. The color ceramic according to claim 1, wherein the average crystal grain size of the alumina crystal is 0.3 μm or more and 0.45 μm or less, and the average distance between the centers of gravity is 0.85 μm or more and 1.0 μm or less.   A decorative article comprising the color ceramics according to claim 1 or 2.