JP4960070B2 - Black ceramics, decorative parts for watches using the same, and methods for producing the black ceramics - Google Patents

Description

  The present invention relates to a black ceramic suitable for decorative parts used for decorative parts for jewelry, decorative parts for watches, decorative parts for building materials, decorative parts for kitchen parts, decorative parts for home appliances, decorative parts for automobiles, etc. In particular, the present invention relates to a decorative part for a watch which is suitably used for a wristwatch case and a band piece and produces a beautiful color tone.

  Traditionally, in European watch jewelry exhibitions, dark watch ornaments have been in the limelight, and recently black watch ornaments are rapidly becoming popular. Black decorative parts have been used as formal colors for a long time among many decorative items that use chromatic colors, and have earned a strong reputation for giving them a simple and sophisticated feeling.

Under such circumstances, various black ceramics used for decorative parts have been proposed. For example, in Patent Document 1, 1 to 5 parts by weight of CoO and 0.25 to 1.0 parts by weight of Fe ₂ O ₃ are added as coloring pigments to 100 parts by weight of a zirconia raw material containing a stabilizer, and Cr _{2 is} further added. Dark colored zirconia ceramics to which O ₃ is added at a ratio of 0.25 to 1.0 parts by weight have been proposed, and light blue, dark blue and dark blue zirconia ceramics are described in the examples.

In Patent Document 2, at least one oxide of Fe, Co, Ni, Cr, Si, Mn, Al, and Zn is combined in an amount of 1 to 10% by weight, carbon is 0.1 to 1% by weight, and stabilized. A zirconia black sintered body containing an agent has been proposed. In the examples, Fe ₂ O ₃ , FeO, Cr ₂ O ₃ , CoO, NiO, SiO ₂ , MnO ₂ , Al ₂ O ₃ and ZnO are proposed. Are disclosed as oxide pigments, and it is described that these oxide pigments are colorants.

In Patent Document 3, a zirconia matrix stabilized with at least one stabilizer selected from the group consisting of oxides consisting of 3-70% by weight of yttrium oxide, magnesium oxide, cerium oxide and calcium oxide, and Made from moldings consisting primarily of 1-10% by weight pigments formed by cobalt oxide and iron oxide powders or spinel CoFe ₂ O ₄ powders with 25-50% by weight cobalt oxide and the balance being iron oxide A decorative article mainly composed of black zirconia formed by a fired product is described.
Japanese Patent No.2761742 Japanese Patent Publication No. 3-9062 Japanese Patent No.3714563

  However, although the dark-colored colored zirconia ceramics described in Patent Document 1 exhibit light blue, dark blue, and dark blue tones, they are not zirconia ceramics that exhibit black, and thus are not accepted by the market where black is required. It was.

  In addition, the zirconia-based black sintered body described in Patent Document 2 has blue, brown and gray having excellent mechanical properties such as zirconia inherently high strength and high toughness, but having a uniform and deep color feeling. It was a blackish-colored black, and it was not a so-called extremely black tone that is popular in recent markets. Furthermore, since the zirconia black sintered body is fired in a nitrogen atmosphere, there is a problem that the production cost is high.

  Further, the decorative article mainly composed of black zirconia described in Patent Document 3 has mechanical properties such as high strength and high toughness inherent to zirconia, and shows black, but slightly. The color tone was bluish and was not close to the so-called extremely black color.

In view of such problems, the present invention brings about a black color tone called extremely black, which can provide a high-class feeling and an aesthetic satisfaction, and as a result, a black ceramic that can provide mental comfort through vision. Another object of the present invention is to provide a decorative part for a watch using the same and a method for producing the black ceramic .

Black ceramic of the present invention, stabilizers and made of zirconia ceramic containing a colorant, wherein the colorant is cobalt oxide _{(CoO, Co} 2 O 3, at least one kind of _Co 3 _{O 4),} oxide Iron (Fe ₂ O ₃ ) and chromium oxide (Cr ₂ O ₃ ) , wherein the cobalt oxide content is 40 to 70% by mass with respect to the total content of the colorant, and the iron oxide content Is 15 to 30% by mass and the content of the chromium oxide is 15 to 30% by mass, the lightness index L * in the color space of CIE1976L * a * b * is 3.0 or more and 4.5 or less, the chromaticness index a * and b * Is respectively -0.5 or more and +0.5 or less and -1.0 or more and +1.0 or less.

The black ceramic of the present invention is characterized in that, in the above configuration, the apparent density of the black ceramic is 5.9 g / cm ³ or more and 6.1 g / cm ³ or less.
The black ceramic of the present invention is characterized in that, in the above configuration, the open porosity on the surface is 0.2% or less.

  Furthermore, the black ceramic of the present invention is characterized in that, in the above configuration, the maximum opening diameter of the open pores on the surface is 50 μm or less.

Further, the decorative part for a watch of the present invention is characterized by comprising the black ceramic of the present invention having any one of the above-described configurations.
Moreover, the manufacturing method of the black ceramics of the present invention includes zirconium oxide (ZrO ₂ ) 91 to 97 mol%, yttrium oxide (Y ₂ O ₃ ), hafnium oxide (HfO ₂ ), cerium oxide (CeO ₂ ), magnesium oxide ( With respect to 100 parts by mass of a composition comprising 3 to 9 mol% of at least one stabilizer selected from MgO) and calcium oxide (CaO),
1 to 2.5 parts by mass of cobalt oxide ( at least one of CoO, Co ₂ O ₃ , Co ₃ O ₄ ), 0.5 to 1.0 part by mass of iron oxide (Fe ₂ O ₃ ), and chromium oxide (Cr ₂ O ₃ ) 0.5
Add ~ 1.0 part by mass and include mixing and crushing using black ceramic balls
It is characterized by that.

According to black ceramics of the present invention, stabilizers and made of zirconia ceramic containing a colorant, wherein the colorant is cobalt oxide _{(CoO, Co} 2 O 3, at least one kind of _Co 3 _{O 4)} , an acid iron _(Fe 2 _{O 3)} and chromium oxide _(Cr 2 _{O 3),} relative to the total amount of the colorant, the content of the cobalt oxide of 40 to 70 wt%, said iron oxide Is 15 to 30% by mass and the chromium oxide content is 15 to 30% by mass, the lightness index L * in the CIE1976L * a * b * color space of the surface is 3.0 to 4.5, and the chromaticness index a Since * and b * are respectively −0.5 or more and +0.5 or less and −1.0 or more and +1.0 or less, the black complex oxides CoO—Fe ₂ O ₃ —Cr ₂ O ₃ , Co ₂ O ₃ — Fe ₂ O ₃ —Cr ₂ O ₃ and Co ₃ O ₄ —Fe ₂ O ₃ —Cr ₂ O ₃ are formed, these act so that the reflectance of light on the surface of the black ceramic is lowered, and the color tone is extremely black. A black color tone is produced, and a moderate brightness can be expressed in the extremely black color tone, so a divine black is obtained . The result is a sense of luxury, aesthetic satisfaction, and mental comfort through sight, which increases popularity in the market .

Further, according to the black ceramic of the present invention, when the apparent density is 5.9 g / cm ³ or more and 6.1 g / cm ³ or less, the black ceramic can be reduced in weight. The owner will also like it.

  Further, according to the black ceramics of the present invention, when the open porosity on the surface is 0.2% or less, the color unevenness due to the contour formed by the pores is reduced and the color tone on the surface becomes dark. Becomes smaller and more textured, so that a high aesthetic satisfaction can be obtained.

Further, according to the black ceramics of the present invention, when the maximum opening diameter of the open pores on the surface is 50 μm or less, the black ceramics of the present invention is used for a wrist watch band piece, so that it is different from other parts by the outline of the pores. The color unevenness due to the difference is reduced, and the difference in color tone between adjacent band pieces is almost eliminated, so that the user does not feel uncomfortable with the color tone even if the parts are replaced.
In addition, according to the decorative part for a watch of the present invention using the black ceramic of the present invention, the black ceramic of the present invention has a high-class feeling and an aesthetic satisfaction can be obtained. Therefore, it can be used particularly suitably as a decorative part for a watch that is required to have a visual aesthetic appearance when worn or placed close to it.
Further, according to the method for producing black ceramics of the present invention, zirconium oxide (ZrO ₂ ) 91 to 97 mol%, yttrium oxide (Y ₂ O ₃ ), hafnium oxide (HfO ₂ ), cerium oxide (CeO ₂ ), oxidation For 100 parts by mass of a composition comprising 3 to 9 mol% of at least one stabilizer selected from magnesium (MgO) and calcium oxide (CaO),
As a colorant, cobalt oxide ( at least one of CoO, Co ₂ O ₃ , and Co ₃ O ₄ ) 1 to 2.5 parts by mass, iron oxide (Fe ₂ O ₃ ) 0.5 to 1.0 parts by mass, and chromium oxide (Cr ₂
O ₃ ) When 0.5 to 1.0 part by mass is added and mixing and pulverization is performed using black ceramic balls, mixing of powder with high brightness can be suppressed, and CIE1976L * a * on the surface can be suppressed. The lightness index L * in the b * color space may be 3.0 or more and 4.5 or less.

  Examples of embodiments of the present invention will be described below.

With black ceramic of the present invention, stabilizers and made of zirconia ceramic containing a colorant, wherein the colorant is a cobalt oxide _{(CoO, Co} 2 O 3, at least one kind of _Co 3 _{O 4)} Subcomponents of the colorant are iron oxide (Fe ₂ O ₃ ) and chromium oxide (Cr ₂ O ₃ ), and the content of the cobalt oxide is 40 to 70 with respect to the total content of the colorant. The content of the iron oxide is 15 to 30% by mass, the content of the chromium oxide is 15 to 30% by mass, and the lightness index L * in the CIE1976L * a * b * color space of the surface is 3.0 or more and 4.5 Hereinafter, the chromaticness indices a * and b * are −0.5 or more and +0.5 or less and −1.0 or more and +1.0 or less, respectively.

The present inventors are able to give black ceramics that give luxury, aesthetic satisfaction, mental comfort, etc. to the owner who seeks decorative value, and that brings out the color tone that is said to be extremely popular in the recent market. As a result of various studies, the zirconia ceramics containing a stabilizer and a colorant are used, and the main component of the colorant is at least one of cobalt oxide (CoO, Co ₂ O ₃ , Co ₃ O ₄ ). In addition, it was found that the above-mentioned object can be achieved by using iron oxide (Fe ₂ O ₃ ) and chromium oxide (Cr ₂ O ₃ ) as subcomponents.

That is, the black ceramic of the present invention is composed of stable components such as yttrium oxide (Y ₂ O ₃ ), hafnium oxide (HfO ₂ ), cerium oxide (CeO ₂ ), magnesium oxide (MgO), and calcium oxide (CaO). An agent, a colorant composed of cobalt oxide (at least one of CoO, Co ₂ O ₃ , Co ₃ O ₄ ), iron oxide (Fe ₂ O ₃ ) and chromium oxide (Cr ₂ O ₃ ), and zirconia Cobalt oxide (CoO, Co ₂ O ₃ , Co ₃ O ₄ ) as a main component of the colorant and iron oxide (Fe ₂ O ₃ ) as a subcomponent and luxury owner seeking decorative value by chromium oxide (Cr 2 _{O 3),} aesthetic satisfaction, given the mind soothing like, moreover It is so as to strike a tone that is said to be popular very black in the near of the market.

  In the present invention, the main component means a component having the highest ratio in 100 parts by mass of the colorant, and the subcomponent means a component other than the main component. In particular, the main component of the colorant is preferably 43% by mass or more and 60% by mass or less in 100% by mass of the colorant.

Although the powder of iron oxide (Fe ₂ O ₃ ) is red and the powder of chromium oxide (Cr ₂ O ₃ ) is green, the composite oxide CoO—Fe ₂ O ₃ —Cr ₂ O ₃ is used in the sintered body. , Co ₂ O ₃ —Fe ₂ O ₃ —Cr ₂ O ₃ and Co ₃ O ₄ —Fe ₂ O ₃ —Cr ₂ O ₃ , and can produce an extremely black color tone.

  Furthermore, each component of the stabilizer and the colorant can be detected by an X-ray diffractometer, a fluorescent X-ray analyzer, a transmission electron microscope (TEM), or the like.

  In the black ceramic of the present invention, the chromaticness indices a * and b * in the CIE1976L * a * b * color space on the surface should be −0.5 to +0.5 and −1.0 to +1.0, respectively. As a result, the reflectance of light on the surface is lowered, and the color tone produces an extremely black color tone. As a result, a sense of luxury, aesthetic satisfaction and mental comfort can be obtained through vision, and high popularity in the market can be obtained.

  Here, the chromaticness index a * is an index indicating the degree of color tone from red to green. When the value of the chromaticness index a * is large in the positive direction, the color tone becomes red, and when the absolute value is small, the color tone is bright. If the chromaticness index a * is large in the negative direction, the color tone becomes green. The reason why the value of the chromaticness index a * is set to −0.5 or more and +0.5 or less is that if it is within this range, a high-quality feeling is obtained, and an astringent color tone with suppressed color vividness can be obtained. If the value of the chromaticness index a * is less than -0.5, the color tone becomes greenish black and lacks astringency, and if it is greater than +0.5, the color tone becomes reddish black, this case also lacks astringency. Because.

  The chromaticness index b * is an index indicating the degree of yellow to blue color tone. When the chromaticness index b * is large in the positive direction, the color tone becomes yellow. When the absolute value is small, the color tone is vivid. The color tone becomes blue when the chromaticness index b * is large in the negative direction. If the chromaticness index b * is set to -1.0 or more and +1.0 or less in this range, as with the chromaticness index a *, there is a high-class feeling and a subtle color tone that suppresses the vividness of the color tone. This is because If the value of chromaticness index a * is less than -1.0, the color tone becomes bluish black and lacks astringency, and if it is greater than +1.0, the color tone becomes yellowish black, and this case also lacks astringency. is there.

  Further, the black ceramic of the present invention is affected by the lightness index L * in the surface CIE1976L * a * b * color space, and when the value of the lightness index L * is in an appropriate range, a divine black is obtained, A sense of luxury increases and aesthetic satisfaction also increases.

  Here, the lightness index L * is an index indicating the lightness and darkness of the color tone. When the value of the lightness index L * is large, the color tone is bright, and when the value of the lightness index L * is small, the color tone is dark.

  In the black ceramic of the present invention, the lightness index L * is preferably 3.0 or more and 4.5 or less. In this range, a moderate brightness appears in the color tone of extremely black, and a godly black color is obtained, so that a high-class feeling is increased and aesthetic satisfaction is further enhanced.

  The values of the chromaticness index a * and b * and the value of the brightness index L * in the CIE 1976 L * a * b * color space on the surface are obtained by measuring in accordance with JIS Z 8722-2000. For example, a color difference meter (former Minolta Co., Ltd. CR-221) is used, the light source is CIE standard light source D65, the illumination light receiving method is condition a ((45-n) [45-0]), and the measurement diameter is It can be measured by setting to 3 mm. If there is no place of an appropriate size for measurement, the measurement may be performed by polishing an arbitrary place.

In addition, the black ceramic of the present invention is affected by the apparent density, and when the value of the apparent density is high, the open pores are reduced and the crystal grain detachment from the end surface of the open pores is suppressed. If the value of the apparent density is lowered, the weight of the black ceramic itself can be reduced, and therefore the apparent density is preferably 5.9 g / cm ³ or more and 6.1 g / cm ³ or less. In addition, what is necessary is just to obtain | require an apparent density based on JISR1634-1998.

  By the way, in the black ceramic of the present invention, the open pores on the surface affect the value of the lightness index L *. When there are many open pores, the color tone of the surface becomes thin due to the influence of color unevenness due to the contours formed by the open pores, so the value of the brightness index L * becomes large. On the other hand, when the number of open pores is small, it is hardly affected by the open pores, the influence of color unevenness due to the contour formed by the open pores is reduced, and the value of the brightness index L * becomes small. By setting the open porosity on the surface to 0.2% or less, the brightness is more preferred. Further, the value of the brightness index L * is preferably 3.0 or more and 4.0 or less, and in this case, the open porosity is preferably 0.1% or less.

  In addition, what is necessary is just to obtain | require the open porosity in the surface based on JISR1634-1998.

  Further, the black ceramic of the present invention is affected by the maximum opening diameter of the open pores on the surface. The smaller the value, the higher the commercial value, and the maximum opening diameter is preferably 50 μm or less. When the maximum opening diameter is 50 μm or less, the color unevenness due to the outline formed by the pores is reduced, and when this black ceramic is a watch band piece, the difference in color tone (homogeneity) between adjacent band pieces is maintained. Because it becomes easier, there is no sense of incongruity even if parts are replaced. The maximum opening diameter of the open pores can be measured using a metal microscope. Specifically, the magnification is set to 100 times, and five areas in which the area per spot is set to 1235 μm × 926 μm are extracted from the surface of the black ceramic, and the diameter of the largest open pore is measured. .

Titanium oxide (TiO ₂ ) may be added to act as a sintering aid and suppress phase transition in the sintering process. The addition ratio is preferably 0.3% by mass or less with respect to 100% by mass of black ceramics.

Further, as inevitable impurities in black ceramics, aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ) and the like are cobalt aluminate (CoAl ₂ O ₄ ), which is a blue complex oxide in black ceramics. Cobalt silicate (CoSiO ₃ ), and these inevitable impurities adversely affect the color of the surface. Therefore, cobalt aluminate (CoAl ₂ O ₄ ) is 0.4% by mass or less with respect to 100% by mass of black ceramics. Cobalt (CoSiO ₃ ) needs to be 0.1 mass% or less.

  In addition to these oxides, allergens such as mercury, nickel, tin, zinc and palladium are inevitable impurities. These allergic metals are each 0.1% by mass or less with respect to 100% by mass of the black ceramic, and the total is preferably 0.5% by mass or less.

  In addition, each ratio of the inevitable impurities of the oxide and the inevitable impurities of the metal can be obtained by semi-quantitative analysis using a fluorescent X-ray analyzer.

  Moreover, it is preferable that the decorative part for a watch of the present invention is made of the black ceramic of the present invention, and examples thereof include a watch case and a watch band piece.

  1A and 1B show an example of a watch case that is a decorative part for a watch of the present invention. FIG. 1A is a perspective view seen from the front side of the watch case, and FIG. 1B is a perspective view seen from the back side of the watch case. FIG. FIG. 2 is a perspective view showing another example of a watch case which is a decorative part for watch of the present invention. FIG. 3 is a schematic view showing an example of the configuration of a watch band that is a decorative part for watch of the present invention. In addition, when showing the same site | part in these, the same referential mark is attached | subjected.

  A watch case 10A shown in FIG. 1 includes a recess 11 for accommodating a movement (drive mechanism) (not shown) and a foot 12 for fixing a watch band (not shown) for mounting a watch on an arm. The concave portion 11 includes a thin bottom portion 13 and a thick body portion 14.

  The watch case 10B shown in FIG. 2 has a hole 15 for receiving a movement (drive mechanism) (not shown) and a watch band (not shown) for attaching a watch to the arm on the body 14. And a foot 12 to be provided.

  Further, the band piece constituting the watch band 50 shown in FIG. 3 is arranged so as to sandwich the middle piece 20 having the through hole 21 into which the pin 40 is inserted and the middle piece 20 between which the both ends of the pin 40 are inserted. The pin 40 is inserted into the through hole 21 of the middle piece 20, and both ends of the inserted pin 40 are inserted into the pin holes 31 of the outer piece 30, thereby The piece 20 and the outer piece 30 are sequentially connected to form a watch band 50.

  By using the black ceramics of the present invention, the watch case 10A, 10B and the watch band 50 can be used as a decorative part and have a high-class feeling and an aesthetic satisfaction can be obtained. As a result, mental comfort can be obtained through vision.

  In the black ceramics according to the present invention, the surface Vickers hardness (Hv) is one of the factors affecting long-term reliability, and the Vickers hardness (Hv) is preferably 8 GPa or more. By making the Vickers hardness (Hv) within this range, the surface is hard to be scratched, so that the decorative surface can easily be scratched even when it comes into contact with a hard material such as dust made of glass or metal. Because there is no. The surface Vickers hardness (Hv) can be measured according to JIS R 1610-2003.

  In addition, the surface of the black ceramics used for various decorative parts including the decorative parts for watches of the present invention refers to the surface where the decorative value of the decorative part is required, and it is necessary to include the surface where the decorative value is not required. Not all aspects. For example, in the case where the black ceramic of the present invention is used for a watch case, the outer surface of the watch case is a surface that is an object of appreciation and requires a decorative value. The inner surface into which is inserted does not normally constitute the outer appearance, and therefore does not correspond to the surface referred to in the present invention unless a decorative value is required for a special reason.

  Next, an example of the manufacturing method of the black ceramic of this invention is demonstrated.

In order to obtain the black ceramic of the present invention, first, 91 to 97 mol% of zirconium oxide (ZrO ₂ ) powder, yttrium oxide (Y ₂ O ₃ ), hafnium oxide (HfO ₂ ), and cerium oxide (CeO) as stabilizers. ₂ ) Cobalt oxide (Co ₂ O ₃ or Co ₃ O as a colorant with respect to 100 parts by mass of a mixed powder composed of 3 to 9 mol% of at least one powder selected from magnesium oxide (MgO) and calcium oxide (CaO) ₄ ) 1 to 2.5 parts by mass of powder, 0.5 to 1.0 parts by mass of iron oxide (Fe ₂ O ₃ ) powder and 0.5 to 1.0 parts by mass of chromium oxide (Cr ₂ O ₃ ) powder, and water as a solvent were added. Mix and grind using a vibration mill, ball mill, etc. Here, it is important to use so-called achromatic ceramic balls of black or white as the balls used for mixing and pulverization, and these balls have a chromaticness index a * and b * on the surface of black ceramics of- This is an important factor for achieving a value of 0.5 to +0.5 and −1.0 to +1.0.

For example, the black ceramic balls include zirconium oxide (ZrO ₂ ) 91 to 97 mol%, yttrium oxide (Y ₂ O ₃ ), hafnium oxide (HfO ₂ ), cerium oxide (CeO ₂ ), magnesium oxide (MgO). And 100 parts by mass of at least one stabilizer selected from calcium oxide (CaO) and 3 parts by mass of cobalt oxide (CoO, Co ₂ O ₃ , Co ₃ O ₄ ) as a colorant. one) 1-2.5 parts by weight or those containing iron oxide _(Fe 2 _{O 3)} 0.5~1.0 parts by mass of chromium oxide _(Cr 2 _{O 3)} 0.5~1.0 parts by weight.

The white ceramic balls include zirconium oxide (ZrO ₂ ) 91 to 97 mol%, yttrium oxide (Y ₂ O ₃ ), hafnium oxide (HfO ₂ ), cerium oxide (CeO ₂ ), magnesium oxide (MgO). And 100 parts by mass of a composition comprising 3 to 9 mol% of at least one stabilizer selected from calcium oxide (CaO).

The cobalt oxide powder represented by the composition formula Co ₂ O ₃ or Co ₃ O ₄ added as a colorant exhibits a black color, and part of the powder decomposes at a temperature of 895 ° C. or higher during the subsequent firing step. In black ceramics, cobalt oxide whose composition formula is represented by CoO exists, but cobalt oxide whose composition formula is represented by CoO, Co ₂ O ₃ , or Co ₃ O ₄ may coexist.

  Further, in order to make the lightness index L * in the CIE1976L * a * b * color space of the surface be 3.0 or more and 4.5 or less, a black ceramic ball is used in order to suppress mixing of powder having high lightness. Is preferred.

  After mixing and pulverizing this raw material, a predetermined amount of paraffin wax is added as a binder, and a disc, flat plate is formed by a desired molding method, for example, dry pressure molding method, cold isostatic pressing method, extrusion molding method, etc. , Formed into a desired shape such as a torus. And after degreasing | defatting the obtained molded object as needed, it baked at the temperature of 1300 degreeC or more and 1500 degrees C or less in air | atmosphere atmosphere, and obtains a sintered compact.

The apparent density of the black ceramic of the present invention is affected by the heating and sintering temperature, and the apparent density increases as this temperature is increased. In order to set the apparent density of the black ceramic to 5.9 g / cm ³ or more and 6.1 g / cm ³ or less, it is preferable to set the heat sintering temperature to 1350 ° C. or more and 1500 ° C. or less. If the heating and sintering temperature is lower than 1350 ° C, the sintering is insufficient and the apparent density of the black ceramic cannot be increased to 5.9 g / cm ³ or more. This is because if it exceeds, the crystals of the sintered body cause abnormal grain growth, the mechanical properties are lowered, and the firing cost is increased. By setting the heat sintering temperature to 1350 ° C. or more and 1500 ° C. or less, the apparent density can be made 5.9 g / cm ³ or more and 6.1 g / cm ³ or less, and the firing cost can be reduced.

  And by carrying out barrel polishing of the obtained sintered body, the surface of the sintered body becomes a beautiful decorative surface that brings out an extremely black color tone, and the black ceramic of the present invention can be obtained.

  If the shape of the black ceramic product is complex, it is molded into a block shape or a shape close to the product shape in advance by a dry pressure molding method, cold isostatic pressing method, extrusion molding method, injection molding method, etc. Then, after firing and grinding so as to obtain a product shape, barrel polishing may be performed. Alternatively, the product shape may be formed by an injection molding method from the beginning, and barrel polishing may be performed after firing.

  Here, before barrel polishing, grinding or lapping may be performed as necessary. For example, a small diamond paste having an average particle size of 1 μm or less may be supplied to a tin lapping machine for lapping. In barrel polishing, a centrifugal barrel polishing machine is used, media and green carborundum (GC) are charged into the centrifugal barrel polishing machine, and the wet polishing may be performed for about 24 hours.

  When the dry pressure molding method is selected as the molding method, the molding pressure affects the open porosity, the maximum open diameter of the open pores, and the Vickers hardness (Hv). When the molding pressure is increased, the open porosity and the maximum opening diameter can be reduced, and the Vickers hardness (Hv) can be increased. In order to obtain the black ceramic of the present invention, it is preferable that the molding pressure is 49 MPa or more and 196 MPa or less. The reason why the molding pressure is 49 MPa or more is that when the molding pressure is less than 49 MPa, the open porosity on the surface of the black ceramic exceeds 0.2%, and the Vickers hardness (Hv) becomes less than 12 GPa.

  The reason why the molding pressure is set to 196 MPa or less is that if it exceeds 196 MPa, the life of the mold is shortened. By setting the molding pressure to 49 MPa or more and 196 MPa or less, the life of the mold can be extended, the open porosity on the surface of the black ceramic can be 0.2% or less, and the Vickers hardness (Hv) can be 12 GPa or more.

  In particular, when the molding pressure is 96 MPa or more, the maximum opening diameter of the open pores on the surface can be made 50 μm or less, which is more preferable.

  The black ceramics of the present invention obtained as described above has a high-class feeling and can provide aesthetic satisfaction, and as a result, mental comfort can be obtained through vision. A watch case that brings out a very black color, a decorative piece for a watch such as a watch band piece, a decorative piece for accessories such as brooches, necklaces, earrings, rings, tie pins, tie tacks, medals, buttons, floors, walls, It can be suitably used as a decorative part for building materials such as tiles or door handles that decorate the ceiling, a decorative part for kitchen parts such as spoons and forks, other decorative parts for home appliances, and decorative parts for automobiles.

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

Example 1
First, with respect to 100 parts by mass of a mixed powder composed of 97 mol% of zirconium oxide (ZrO ₂ ) powder and 3 mol% of yttrium oxide (Y ₂ O ₃ ) powder as a stabilizer, the colorant shown in Table 1 and the solvent The mixture was pulverized with a vibration mill. Table 1 shows the types and colors of the ceramic balls used for the mixing and grinding, and the ratio of the colorant in the black ceramic (sintered body).

  The colorant ratios shown in Table 1 are values obtained by semi-quantitative analysis using a fluorescent X-ray analyzer.

  After mixing and pulverizing this raw material, a predetermined amount of paraffin wax is added as a binder, and a molded body of the middle piece 20 and the outer piece 30 of the band piece is produced at a pressure of 98 MPa by a dry pressure molding method, and the obtained molded body Was fired at 1450 ° C. to obtain a sintered body. Then, together with the obtained sintered body, media and green carborundum (GC) were put into a centrifugal barrel polishing machine, and barrel polishing was performed for 24 hours in a wet manner to obtain a band piece.

  Then, using a color difference meter (formerly Minolta Co., Ltd. CR-221), the light source is CIE standard light source D65, the illumination light receiving method is condition a ((45-n) [45-0]), and the measurement diameter is The color tone of the surface was measured according to JIS Z 8722-2000, setting to 3 mm.

Regarding the color tone, we conducted a questionnaire survey on three items, high-quality, aesthetic satisfaction, and mental comfort, on a total of 40 monitors, 5 European men and women for each age group in their 20s to 50s. The ratio of monitors that answered “feel” to this item is shown in Table 1, and 80% or more of the ratio was evaluated as good.

  As can be seen from the results shown in Table 1, sample Nos. Chromaticity indices a * and b * are outside the range of −0.5 or more and +0.5 or less and −1.0 or more and +1.0 or less, respectively. Since 1, 2, 13, and 14 cannot be said to be extremely black, the monitor could not be satisfied sufficiently.

  On the other hand, sample Nos. With chromaticness indices a * and b * of −0.5 to +0.5 and −1.0 to +1.0, respectively. Nos. 3 to 12 were good results that gave the monitor a high-class feeling, aesthetic satisfaction, and mental comfort because the color tone was extremely black.

  In particular, Sample No. in which cobalt oxide is 43% by mass or more and 60% by mass or less in 100% by mass of the colorant. Samples Nos. 5 to 10 are samples No. 5 whose evaluations of luxury, aesthetic satisfaction, and mental comfort are outside this range. Higher than 3, 4, 11, and 12 is preferable.

  In addition, sample Nos. 1 and 2 having the same colorant ratio and different ceramic ball colors. 3 and sample no. 4 and sample no. 5 and sample no. 6 and sample no. 7 and sample no. 8 and sample no. 9 and sample no. Compared with 10, the sample using the black ceramic ball has a lower lightness index L * than the sample using the white ceramic ball, and more than 3.0 to 4.5, so all the above evaluations are high and suitable. is there.

(Example 2)
First, 100 mass of mixed powder composed of 97 mol% of zirconium oxide (ZrO ₂ ) powder, 2.5 mol% of yttrium oxide (Y ₂ O ₃ ) powder and 0.5 mol% of hafnium oxide (HfO ₂ ) powder as stabilizers. The colorant shown in Table 2 and water as a solvent were added to the part, and mixed and ground using a black zirconia ball in a vibration mill. In addition, in order to investigate the influence of unavoidable impurities on some samples, aluminum oxide (Al ₂ O ₃ ) and silicon oxide (SiO ₂ ) powders were consciously added as impurities to influence the sintered body. I investigated. When these oxide powders are heated in the presence of cobalt oxide (CoO), they react with cobalt oxide (CoO), respectively, to produce blue complex oxides such as cobalt aluminate (CoAl ₂ O ₄ ) and silicic acid. Cobalt (CoSiO ₃ ) is produced.

  The ratio of the colorant and impurities in the sintered body is as shown in Table 2, and is a value obtained by semi-quantitative analysis using a fluorescent X-ray analyzer.

  After mixing and pulverizing this raw material, a predetermined amount of paraffin wax was added as a binder, and a molded body of the band piece 20 and the outer piece 30 was produced by the pressure shown in Table 2 by a dry pressure molding method. The molded body was fired at a temperature shown in Table 2 to obtain a sintered body. Then, together with the obtained sintered body, media and green carborundum (GC) were put into a centrifugal barrel polishing machine, and barrel polishing was performed for 24 hours in a wet manner to obtain a band piece.

  The apparent density of the band piece and the open porosity on the surface of the band piece were measured in accordance with JIS R 1634-1998.

  The maximum opening diameter of the open pores on the surface was measured using a metal microscope. Specifically, the magnification was set to 100 times, and five areas where the area per area was set to 1235 μm × 926 μm were extracted from the surface, the diameter of the largest open pore was measured, and the value was maximized. The caliber was taken.

  In addition, degranulation was observed in the above measurement range, and △ indicates that degranulation was observed and ◯ indicates that degranulation was not observed.

  And the color tone of the surface was measured by the method shown in Example 1 using the color difference meter (former Minolta Co., Ltd. product CR-221).

  Further, the same questionnaire survey as in Example 1 was conducted for the color tone.

In addition, for a watch connected with a watch band piece having an apparent density of 5.9 g / cm ³ or more and 6.0 g / cm ³ or less, an open porosity on the surface and a maximum opening diameter of the open pore of 0.2% or less and 50 μm or less, respectively. A band was prepared, and sample No. We replaced it with 15-27 and conducted a questionnaire survey to see if the color tone seemed uncomfortable.

Table 3 shows the measured values and the survey results obtained by the above method.

  As can be seen from the results shown in Tables 2 and 3, Sample Nos. With a molding pressure as low as 33 MPa. 17 could not be molded properly.

Sample No. with an apparent density of less than 5.9 g / cm ³ was used. Sample No. 15 in which the grain size of the surface of the black ceramic was degranulated, whereas the apparent density was 5.9 g / cm ³ or more. In 16, 18 to 27, degranulation was not observed, and it was good.

Sample No. with an apparent density of 6.1 g / cm ³ or less was used. Needless to say, the weight reduction of Samples 18 and 26 does not impair the commercial value significantly.

  Sample No. with an open porosity on the surface of 0.2% or less. Nos. 16 and 18 to 27 have a low color index L * because the color tone on the surface is deep, and the aesthetic satisfaction is that sample No. It was higher than 15 and good.

Sample No. with a maximum opening diameter of the open pores on the surface exceeding 50 μm. Sample Nos. 15 and 18 in which the impurity cobalt aluminate (CoAl ₂ O ₄ ) exceeds 0.4 mass%. 22 and Sample No. in which cobalt silicate (CoSiO ₃ ), which is also an impurity, exceeds 0.1% by mass. When the watch 24 was newly incorporated into the watch band, some monitors felt uncomfortable in color tone, but sample No. No. with a maximum opening diameter of 50 μm or less was used. Nos. 16, 19 to 21, 23, 25 to 27 were good because there was no monitor that felt uncomfortable in color tone even if they were newly incorporated in a watch band.

(A) is the perspective view which looked at an example of the timepiece case which is a decorative part for timepieces of this invention which looked at the timepiece case from the front side, (b) is the perspective view which looked at the timepiece case of (a) from the back side FIG. It is a perspective view which shows the other example of the case for timepieces which is the decorative component for timepieces of this invention. It is a schematic diagram which shows an example of a structure of the timepiece band which is the decorative component for timepieces of this invention.

Explanation of symbols

10A, 10B: Watch case
11: Recess
12: Foot
13: Bottom
14: Torso
15: Hole
20: Nakakoma
21: Through hole
30: Outer piece
31: Pin hole
40: Pin
50: Watch band

Claims (6)

Stabilizers and made of zirconia ceramic containing a colorant, wherein the colorant is cobalt oxide _{(CoO, Co 2 O 3,} Co 3 O at least one kind of ₄₎ and an acid iron _(Fe 2 _{O 3} ) And chromium oxide (Cr ₂ O ₃ ) , wherein the cobalt oxide content is 40 to 70 mass% and the iron oxide content is 15 to 30 mass% with respect to the total content of the colorant. And the chromium oxide content is 15-30% by mass, the lightness index L * in the color space of CIE1976L * a * b * is 3.0 or more and 4.5 or less, and the chromaticness index a * and b * is Black ceramics characterized by being -0.5 or more and +0.5 or less and -1.0 or more and +1.0 or less, respectively. 2. The black ceramic according to claim 1, wherein the black ceramic has an apparent density of 5.9 g / cm ³ or more and 6.1 g / cm ³ or less. The black ceramics according to claim 1 or 2 , wherein an open porosity on the surface is 0.2% or less. The black ceramic according to any one of claims 1 to 3 , wherein a maximum opening diameter of the open pores on the surface is 50 µm or less. A decorative part for a watch, comprising the black ceramic according to any one of claims 1 to 4 .   It is a manufacturing method of the black ceramics of Claims 1-4, Comprising: A zirconium oxide (ZrO) ₂ ) 91-97 mol% and yttrium oxide (Y ₂ O ₃ ), Hafnium oxide (HfO) ₂ ), Cerium oxide (CeO) ₂ ), Magnesium oxide (MgO) and calcium oxide (CaO), and 100 parts by mass of at least one stabilizer selected from 3 to 9 mol%, cobalt oxide (CoO, Co as colorant) ₂ O ₃ , Co ₃ O ₄ 1 to 2.5 parts by mass of iron oxide (Fe) ₂ O ₃ ) 0.5-1.0 parts by mass and chromium oxide (Cr ₂ O ₃ ) A method for producing black ceramics, comprising the step of adding 0.5 to 1.0 part by mass and mixing and grinding using black ceramic balls.

Images