Ceramic composite, a wristwatch or nameplate comprising the ceramic composite, and a method for manufacturing the ceramic composite

Abstract

To provide a ceramic composite in which an eutectic lamellar structure can be visually recognized in a visible light wavelength region and the eutectic lamellar structure can be visually utilized even in a light emitting state, and its producing method, and a wristwatch or a name plate provided with the ceramic composite.SOLUTION: A plurality of dies having slits and arranged in parallel with each other in a longitudinal direction are housed in a crucible, and a raw material of a ceramic composite is put into the crucible. Next, the crucible is heated to melt the raw material in the crucible to prepare a melt. Next, a melt pool in which the melt is pooled in an upper part of the slit through the slit is formed, a seed crystal is brought into contact with the melt pool, and a pull-up step of pulling up the seed crystal is performed to produce a base material of the ceramic composite. Further, the base material is cut to produce a ceramic composite which has two oxide phases as a lamellar structure, the two oxide phases being white or transparent when irradiated with visible light having a wavelength of 380 nm or more and 780 nm or less.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a ceramic composite, a wristwatch or nameplate including the ceramic composite, and a method for manufacturing the ceramic composite.

Background Art

[0002] Currently, lighting devices that use a light-emitting diode (LED) or semiconductor laser that emits blue light as a light source, wavelength-convert part of the blue light to yellow light using a wavelength conversion member, and irradiate white light by mixing the blue light and yellow light are widespread. In such lighting devices, it has been proposed to use a phosphor material of a YAG (Y3Al5O 12 )-based system and contain phosphor powder in resin or glass.

[0003] Also, in Patent Document 1 or 2, a ceramic composite having a lamellar structure in which the Y3Al5O 12 phase and the Al2O3 phase are continuously and three-dimensionally intertwined with each other as a eutectic has been proposed. In the ceramic composite described in Patent Document 1 or 2, the Y3Al5O 12 phase wavelength-converts blue light to yellow light, and blue light and yellow light are scattered at the interface between the Y3Al5O 12 phase and the Al2O3 phase to obtain white light by color mixing. Further, at least one of the eutectics is a phosphor phase composed of an oxide activated with a fluorescence-emitting additive (for example, Ce or the like).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional ceramic composite, the appearance color is colored by the activator. Therefore, under natural light in the visible light wavelength range of 380 nm or more and 780 nm or less, the entire appearance color was visually observed in a so-called solid-color state where it was uniformly colored by the activator. Therefore, it was impossible to visually recognize the eutectic lamellar structure with the naked eye under natural light in the visible light wavelength range.

[0006] Also, in the light-emitting state of the conventional ceramic composite, only light emitted by wavelength conversion and color mixing was emitted, and the eutectic lamellar structure could not be utilized visually.

[0007] Therefore, the present invention has been made in view of the above-described conventional problems, and it is possible to visually recognize the eutectic lamellar structure with the naked eye in the visible light wavelength range, and it is also possible to utilize the eutectic lamellar structure visually even in the light-emitting state. An object of the present invention is to provide a ceramic composite, a method for manufacturing the same, and a wristwatch or nameplate including the ceramic composite.

Means for Solving the Problems

[0008] In order to solve the above problems, the ceramic composite of the present invention has two oxide phases in a lamellar structure, and is characterized in that the two oxide phases are white or transparent when irradiated with visible light having a wavelength of 380 nm or more and 780 nm or less.

[0009] Also, the wristwatch or nameplate of the present invention is characterized by including the ceramic composite.

[0010] The manufacturing method of the ceramic composite of the present invention further comprises the steps of: accommodating a plurality of dies, each having a slit and arranged with their longitudinal directions parallel to each other, in a crucible, and introducing a raw material of the ceramic composite into the crucible; heating the crucible to melt the raw material in the crucible to prepare a melt; forming a melt pool for accumulating the melt above the slit through the slit; manufacturing a base material of the ceramic composite by a lifting step of bringing a seed crystal into contact with the melt pool and lifting the seed crystal; and further cutting the base material of the ceramic composite to manufacture a ceramic composite having two oxide phases in a lamellar structure and being white or transparent when irradiated with visible light having a wavelength of 380 nm or more and 780 nm or less.

Advantages of the Invention

[0011] According to the ceramic composite of the present invention, the wristwatch or nameplate provided with the ceramic composite, and the manufacturing method of the ceramic composite, a ceramic composite in which the eutectic lamellar structure can be visually recognized with the naked eye in the wavelength range of visible light can be realized and provided.

[0012] Furthermore, even in the light-emitting state of the ceramic composite, the eutectic lamellar structure can be visually recognized with the naked eye. Therefore, even in the light-emitting state of the ceramic composite, the eutectic lamellar structure can be utilized visually.

Brief Description of the Drawings

[0013]

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Figure 11

Mode for Carrying Out the Invention

[0014] The first feature of the present embodiment is a ceramic composite having two oxide phases in a lamellar structure, and when irradiated with visible light having a wavelength of 380 nm or more and 780 nm or less, the two oxide phases are white or transparent.

[0015] The second feature is that among the two oxide phases, when irradiated with visible light, the first oxide phase is transparent and the second oxide phase is white, and when irradiated with ultraviolet light having a wavelength of 315 nm or more and less than 380 nm, the first oxide phase emits colored light.

[0016] The third feature is that among the two oxide phases, when irradiated with visible light, the first oxide phase is white and the second oxide phase is transparent, and when irradiated with ultraviolet light having a wavelength of 315 nm or more and less than 380 nm, the first oxide phase emits colored light, which is a ceramic composite.

[0017] The fourth feature is that the first oxide phase is a (Gd 1-x ,Tb x )AlO3 phase (0 < x < 1), the second oxide phase is an Al2O3 phase, and the (Gd 1-x ,Tb x )AlO3 phase emits colored light with a wavelength of 493 nm or more and 624 nm or less when irradiated with ultraviolet light, which is a ceramic composite.

[0018] The fifth feature is that the outer shape is plate-like and it is a ceramic composite having at least one surface.

[0019] The sixth feature is a wristwatch or nameplate including any of the above ceramic composites.

[0020] The seventh feature is a method for manufacturing a ceramic composite, which includes a step of accommodating a plurality of dies having slits and arranged with their longitudinal directions parallel to each other in a crucible, and charging a raw material of the ceramic composite into the crucible; a step of heating the crucible to melt the raw material in the crucible to prepare a melt; a step of forming a melt pool for accumulating the melt above the slit through the slit; a step of pulling up the ceramic composite base material by bringing a seed crystal into contact with the melt pool and pulling up the seed crystal, and further cutting the ceramic composite base material to obtain a ceramic composite having two oxide phases in a lamellar structure and being white or transparent when irradiated with visible light having a wavelength of 380 nm or more and 780 nm or less.

[0021] The eighth feature is that the raw material contains Gd2O3, Tb4O7, and Al2O3, and the first oxide phase in the two oxide phases is a (Gd 1-x ,Tbx )It is about a method for manufacturing a ceramic composite in which the first oxide phase is an AlO3 phase and the second oxide phase is an Al2O3 phase.

[0022] Also, the ninth feature is that the (Gd 1-x ,Tb x )AlO3 phase is transparent and the Al2O3 phase is white, which is about a method for manufacturing a ceramic composite.

[0023] Also, the tenth feature is that the (Gd 1-x ,Tb x )AlO3 phase is white and the Al2O3 phase is transparent, which is about a method for manufacturing a ceramic composite.

[0024] According to these configurations or methods, it is possible to realize a ceramic composite in which the eutectic lamellar structure can be visually recognized by the naked eye in the wavelength range of visible light, and it is possible to provide it.

[0025] Furthermore, even in the light-emitting state of the ceramic composite, the eutectic lamellar structure can be visually recognized by the naked eye. Therefore, even in the light-emitting state of the ceramic composite, the eutectic lamellar structure can be utilized visually.

[0026] Furthermore, it is possible to vary the lamellar structure, the interface density of the oxide phase, and the light-emitting state during ultraviolet light irradiation that appear on the surface of the ceramic composite produced from the base material depending on the direction of cutting the base ceramic composite 2.

[0027] Therefore, the decorativeness of application products (for example, watches or nameplates, etc.) equipped with such a ceramic composite can be improved. Furthermore, since a color change can be generated in the ceramic composite with the emission by a black light in the dark, it is suitable as an effect material or a decorative material for entertainment applications. Or, by changing the impression between day and night, it is possible to comprehensively improve the decorativeness regardless of time.

[0028] Furthermore, since one of the two oxide phases can be made transparent, it can be used for a variety of purposes as a kind of skeleton material, which can broaden the range of designs and further improve decorativeness.

[0029] Furthermore, the lamellar structure and oxide phases appear randomly in each ceramic composite matrix. Therefore, the lamellar structure and oxide phases on the surface of each ceramic composite manufactured from that matrix also appear randomly. This makes it possible to identify the manufacturer and owner of a product using such a ceramic composite, preventing counterfeiting and improving security. It also makes it possible to add value to the product, such as a one-off production.

[0030] Furthermore, when the ceramic composite is irradiated with ultraviolet light, it can emit colored light with a wavelength of 493 nm to 624 nm. Furthermore, the luminescence state and intensity can be changed depending on the difference in luminescence (particularly the difference in wavelength) between each oxide phase and the cutting direction from the base material. Therefore, it is possible to further improve the decorativeness.

[0031] Furthermore, it is desirable that the outer shape of the ceramic composite obtained by cutting, grinding, and polishing the base material be plate-shaped and have at least one surface (the main surface). The reason for this is that by making the outer shape of the ceramic composite plate-shaped, the main surface can be made relatively large. Therefore, the lamellar structure and oxide phase can be exposed throughout the entire surface area, and the improved visibility of the lamellar structure and oxide phase makes it possible to further improve added value such as decorativeness, identification of the manufacturer or owner, and one-off production.

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to Figures 1 to 10. The same or equivalent components, members, and processes shown in the drawings will be denoted by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0033] First, the manufacturing apparatus used in the manufacturing method according to this embodiment will be described with reference to FIGS. 1 to 7. FIGS. 1 to 7 are diagrams for explaining a ceramic composite and a manufacturing method thereof according to an embodiment of the present invention.

[0034] As shown in FIG. 1, the manufacturing apparatus 1 for a ceramic composite is composed of a growth container 3 for growing the ceramic composite 2 and a lifting container 4 for lifting the grown ceramic composite 2, and manufactures the ceramic composite 2 by crystal growth using the EFG (Edge-defined Film-fed Growth) method.

[0035] The growth container 3 includes a crucible 5, a crucible driving unit 6, a heater 7 (metal or carbon), an electrode 8, a die 9, and a heat insulating material 10 (oxide or carbon). The crucible 5 is made of molybdenum (Mo) or tungsten (W) and melts the raw material. The crucible driving unit 6 rotates the crucible 5 about its vertical axis. The heater 7 heats the crucible 5. Also, the electrode 8 energizes the heater 7. The die 9 is installed in the crucible 5 and determines the liquid surface shape of the raw material melt (hereinafter, simply referred to as "melt" as necessary) 21 when the ceramic composite 2 is lifted. Further, the heat insulating material 10 surrounds the crucible 5, the heater 7, and the die 9.

[0036] Furthermore, the growth container 3 includes an atmosphere gas inlet 11 and an exhaust port 12. The atmosphere gas inlet 11 is an inlet for introducing, as the atmosphere gas, for example, argon gas or a reducing gas (such as 1.0% hydrogen) into the growth container 3 to prevent oxidation and consumption of the crucible 5, the heater 7, and the die 9. On the other hand, the exhaust port 12 is provided for exhausting the inside of the growth container 3.

[0037] The lifting container 4 includes a shaft 13, a shaft driving unit 14, a gate valve 15, and a substrate entrance / exit 16, and lifts a plurality of flat ceramic composites 2 grown from a seed crystal 17. The shaft 13 holds the seed crystal 17. The shaft driving unit 14 raises and lowers the shaft 13 toward the crucible 5 and rotates the shaft 13 about its lifting direction as an axis. The gate valve 15 separates the growth container 3 and the lifting container 4. The substrate entrance / exit 16 allows the seed crystal 17 to be inserted and removed.

[0038] The manufacturing apparatus 1 also has a control unit (not shown), and the control unit controls the rotation of the crucible driving unit 6 and the shaft driving unit 14.

[0039] Next, the die 9 will be described. The die 9 is made of molybdenum and has a number of partition plates 18 as shown in FIG. 2. In FIG. 2, as an example of the die, there are 30 partition plates 18 and 15 dies 9 are formed. The partition plates 18 have the same flat shape and are arranged parallel to each other so as to form minute gaps (slits) 19, forming one die 9. The slit 19 is provided over substantially the entire width of the die 9. Further, since the plurality of dies 9 have the same shape and are arranged in parallel at a predetermined interval so that their longitudinal directions are parallel to each other, a plurality of slits 19 are provided. The symbol t in FIGS. 2 and 3 indicates the thickness of the die 9. The symbol D in FIG. 2 indicates the gap between the dies 9. The symbol T in FIG. 3 indicates the thickness of the seed crystal 17.

[0040] An inclined surface 30 is formed at the upper part of each partition plate 18, and an acute-angle opening 20 is formed by arranging the inclined surfaces 30 of each other to face each other. The slit 19 has a role of raising the melt 21 from the lower end of each die 9 to the opening 20 by capillary action.

[0041] The raw material of the ceramic composite to be put into the crucible 5 melts (raw material melt) based on the temperature rise of the crucible 5 and becomes the melt 21. A part of this melt 21 infiltrates into the slit 19 of the die 9, rises in the slit 19 based on capillary action as described above, and is exposed from the opening 20, and a raw material melt pool 22 is formed at the opening 20 (see Fig. 4(a)).

[0042] In the EFG method, the ceramic composite 2 grows according to the shape of the melt surface formed by the raw material melt pool (hereinafter, referred to as "melt pool" as necessary) 22. In the die 9 shown in Fig. 2, since the shape of the melt surface is an elongated rectangle, a flat-plate-shaped ceramic composite 2 is manufactured.

[0043] Next, the seed crystal 17 will be described. As shown in Figs. 1, 3 to 6 in this embodiment, a substrate made of a flat-plate-shaped ceramic composite is used as the seed crystal 17. Further, the seed crystal 17 is arranged so that the plane direction of the seed crystal 17 and the longitudinal direction of the die 9 are orthogonal to each other at an angle of 90°. Also, since the seed crystal 17 and the ceramic composite 2 are also orthogonal to each other at an angle of 90°, the side surface of the ceramic composite 2 is shown in Fig. 1. Note that the reference numeral 28 in Figs. 3 and 4 is the crystal plane of the seed crystal 17.

[0044] If the contact area between the seed crystal 17 and the substrate holder (not shown) at the lower part of the shaft 13 is large, the seed crystal 17 will deform due to stress caused by the difference in thermal expansion coefficient, and in some cases, it will be damaged. On the contrary, the fixing of the seed crystal 17 may be loosened due to the difference in thermal expansion coefficient. Therefore, it is preferable that the contact area between the seed crystal 17 and the substrate holder is small. Also, the seed crystal 17 needs to have a substrate shape that can be securely fixed to the substrate holder.

[0045] As shown in Fig. 4, a notch 23 is provided at the upper part of the seed crystal 17. By using this notch 23, for example, a U-shaped substrate holder can be inserted from the lower side of two notches 23, and it becomes possible to securely hold the seed crystal 17 while reducing the contact area.

[0046] Next, a method for manufacturing the ceramic composite 2 using the manufacturing apparatus 1 will be described. First, granulated raw material powder (as an example, a powder containing desired amounts of aluminum oxide (Al2O3), gadolinium oxide (Gd2O3), and terbium oxide (Tb4O7) and mixed), which is a raw material of the ceramic composite, is charged into the crucible 5 storing the die 9 in a predetermined amount for filling. The raw material powder may contain compounds and elements other than the above according to the purity or composition of the ceramic composite to be manufactured.

[0047] Subsequently, in order not to oxidize and consume the crucible 5, the heater 7, or the die 9, the inside of the growth container 3 is replaced with argon gas to make the oxygen concentration equal to or lower than a predetermined value.

[0048] Next, the crucible 5 is heated by the heater 7 to a predetermined temperature to melt the raw material powder in the crucible. The heating temperature of the crucible 5 is set to a temperature equal to or higher than the melting point of all raw material types (in the case of the raw material powder in the above example, for example, 2500°C).

[0049] After heating for a while, the raw material powder melts to prepare a melt 21 of the raw material. Further, a part of the melt 21 rises through the slit 19 of the die 9 by capillary action to reach the surface of the die 9, and a melt pool 22 storing the melt 21 is formed above the slit 19.

[0050] Next, as shown in FIGS. 3 and 4, while holding the seed crystal 17 at an angle perpendicular to the longitudinal direction of the melt pool 22 above the slit 19, it is lowered and the seed crystal 17 is brought into contact with the melt surface of the melt pool 22. The seed crystal 17 is previously introduced into the lifting container 4 from the substrate entrance / exit 16. In FIG. 3, for the sake of easy viewing of the slit 19 and the opening 20, the illustration of the melt 21 and the melt pool 22 is omitted.

[0051] Figures 3 and 4 are diagrams showing the positional relationship between the seed crystal 17 and the partition plate 18. As described above, by making the plane direction of the seed crystal 17 orthogonal to the longitudinal direction of the partition plate 18, it becomes possible to reduce the contact area between the seed crystal 17 and the melt 21. Therefore, the contact portion of the seed crystal 17 conforms to the melt 21, and crystal defects are less likely to occur in the ceramic composite 2 that grows and develops.

[0052] When bringing the seed crystal 17 into contact with the melt surface, the lower part of the seed crystal 17 may be brought into contact with the upper part of the partition plate 18 and melted. Figure 4(b) is a diagram showing the state of melting a part of the seed crystal 17. By melting a part of the seed crystal 17 in this way, the temperature difference between the seed crystal 17 and the melt 21 can be quickly eliminated, and it becomes possible to further reduce the occurrence of crystal defects in the ceramic composite 2.

[0053] Subsequently, the substrate holder is pulled up at a desired pulling speed to start pulling up the seed crystal 17. Specifically, the shaft 13 is used to raise the substrate holder and the seed crystal 17 at a desired pulling speed.

[0054] The substrate holder is raised at a desired pulling speed, and crystal growth (spreading) is performed so that the ceramic composite 2 expands in the longitudinal direction of the die 9 as shown in FIG. 5 with the seed crystal 17 as the center. When the ceramic composite 2 expands to the full width of the die 9 (the end of the partition plate 18) (full spread), a flat-plate-shaped ceramic composite 2 having a width comparable to the full width of the die 9 and a large area is grown (straight-barrel process). FIG. 5 is a schematic diagram showing the state in which the width of the ceramic composite 2 expands by the spreading process. By obtaining a wide ceramic composite 2, the yield of the ceramic composite product is improved.

[0055] By the spreading process, the ceramic composite 2 is grown to the full width of the die 9. Then, as shown in FIG. 6, a flat-plate-shaped straight-barrel portion 26 having a constant width comparable to the full width of the die 9 is pulled up to a desired length (straight-barrel length) at a desired pulling speed to obtain a flat-plate-shaped ceramic composite 2.

[0056] During the lifting process, temperature control is performed using a heater 7 or the like so that the interface temperature of the melt 21 in the melt pool 22 formed above the slit 19 remains constant. The ceramic composite 2 grows as the melt 21 that has risen to the melt pool 22 comes into contact with the seed crystal 17 and is cooled while being lifted. Therefore, by controlling the temperature of the melt pool 22 to be constant, the crystal growth conditions can be kept equivalent during the growth period of the ceramic composite 2, and a lamellar structure composed of two oxide phases can be formed throughout the ceramic composite 2.

[0057] Thereafter, the obtained ceramic composite 2 is allowed to cool, the gate valve 15 is opened, it is moved to the side of the lifting container 4, and taken out from the substrate entrance / exit 16. The appearance of the obtained flat plate-shaped ceramic composite 2 is shown in FIG. 6. The straight body length is not particularly limited, but is preferably 10 mm or more and 1500 mm or less.

[0058] Also, as shown in FIG. 7, the entire width of the die 9 and the width of the seed crystal 17 may be made the same, and the ceramic composite 2 may be grown and grown with the same width as the entire width of the seed crystal 17. In FIG. 7, for the sake of easy visibility of the slit 19, the illustration of the melt 21 and the melt pool 22 is omitted.

[0059] Next, each ceramic composite 2 in FIG. 6 is separated from the seed crystal 17, and each ceramic composite 2 is cut, ground, and polished to obtain a ceramic composite having desired longitudinal and transverse dimensions and thickness as shown in FIG. 8 or FIG. 10, with the ceramic composite 2 as the base material. The ceramic composites in FIGS. 8 and 10 both form a lamellar structure composed of two oxide phases.

[0060] By using the manufacturing apparatus 1, the seed crystal 17, and the die 9 as described above, a plurality of ceramic composites 2 can be simultaneously manufactured from a common seed crystal 17. Therefore, it is possible to reduce the manufacturing cost of each ceramic composite 2.

[0061] Furthermore, in the EFG method, a plurality of ceramic composites 2 are grown and cultivated. Therefore, the plurality of ceramic composites 2 are uniformly cooled and allowed to cool, thereby making it possible to obtain a lamellar structure with reduced variation.

[0062] The die 9, including the seed crystal 17 and the partition plate 18, must be precisely positioned. As shown in FIG. 1 , the manufacturing apparatus 1 is provided with a crucible drive unit 6 that rotates the crucible 5 in which the die 9 is placed, and a control unit (not shown) that controls the rotation. The shaft 13 is also provided with a shaft drive unit 14 that rotates the shaft 13, and a control unit (not shown) that controls the rotation. That is, the positioning of the seed crystal 17 relative to the die 9 is adjusted by rotating the shaft 13 or the crucible 5 using the control unit.

[0063] Incidentally, precise positioning of the seed crystal 17 and the die 9 can also be achieved by using a die 9 in which part of the inclined surface 30 of each partition plate 18 is cut out.

[0064] The planar shape and size of the ceramic composite 2 are not limited, but a rectangular shape with a width of 0.5 mm to 300 mm and a length of 10 mm to 1500 mm is desirable in order to prevent deterioration of workability of the ceramic composite 2. A width of less than 0.5 mm leads to deterioration in productivity of the ceramic composite 2. On the other hand, a width of more than 300 mm deteriorates the uniformity of temperature at the tip (die top) of the die 9, making it more likely that thickness variations will occur and making it difficult to grow the ceramic composite 2. Furthermore, the length is desirable in order to prevent deterioration of workability of the ceramic composite 2.

[0065] Since the ceramic composite 2 of this embodiment is manufactured using the EFG method, it is possible to easily obtain a ceramic composite 2 with a large area by increasing the width of the die 9 and the pulling length.

[0066] Also, although the thickness of the ceramic composite 2 is not limited, a range of 0.2 mm or more and 5.0 mm or less is preferred. When the thickness of the ceramic composite 2 is less than 0.2 mm, crystal growth control becomes difficult in the EFG method, and the influence of the thickness due to manufacturing errors and the influence of thickness unevenness in the plane increase, making it difficult to obtain uniform reflected light across the entire plane of the ceramic composite 2.

[0067] Next, the ceramic composite obtained by the above manufacturing method will be described with reference to FIGS. 8 and 10.

[0068] As shown in FIG. 8 or FIG. 10, the ceramic composite according to the embodiment of the present invention is configured to have two oxide phases in a lamellar structure.

[0069] FIG. 8 or FIG. 10 is a photograph showing the surface of the ceramic composite obtained by the above-described EFG method. In the ceramic composite of this embodiment, a first oxide phase and a second oxide phase exist as a eutectic, and the two oxide phases (the first oxide phase and the second oxide phase) have a lamellar structure that is three-dimensionally intertwined with each other. Further, the first oxide phase and the second oxide phase also have regions that are independently separated in an island shape and regions that are continuous in the two-dimensional or three-dimensional direction.

[0070] The lamellar structures appearing on the surfaces of the ceramic composites in FIGS. 8 and 10 are different depending on the direction of cutting the ceramic composite 2 that serves as the base material. FIG. 8 is a sample produced by cutting, grinding, and polishing the ceramic composite 2 so that the plate surface of the ceramic composite 2 becomes the surface of each ceramic composite as it is. On the other hand, FIG. 10 is a sample produced by cutting, grinding, and polishing the ceramic composite 2 so that a cross-section perpendicular to the length direction (growth direction) of the straight body portion 26 of the ceramic composite 2 becomes the surface of each ceramic composite.

[0071] The photographs of the ceramic composites in Figures 8 and 10 were taken under fluorescent lamps that emit light in the visible wavelength range of 380 nm to 780 nm. From Figures 8 and 10, it is clear that the two oxide phases are white or transparent when illuminated with visible light with a wavelength of 380 nm to 780 nm. The transparent oxide phases are the oxide phases in the relatively dark gray areas photographed in Figures 8 and 10, and text printed on paper can be read with the naked eye through the ceramic composites in Figures 8 and 10.

[0072] In the present invention, visible light refers to light in the wavelength range of 380 nm to 780 nm, and includes light emitted from fluorescent lamps as long as it has a wavelength range of 380 nm to 780 nm.

[0073] When irradiated with visible light, each ceramic composite in Figure 8 shows that of the two oxide phases, the first oxide phase is transparent and the second oxide phase is white. On the other hand, when irradiated with visible light, each ceramic composite in Figure 10 shows that of the two oxide phases, the first oxide phase is white and the second oxide phase is transparent. Thus, the state in which the two oxide phases are visually recognized by the naked eye differs depending on the plane direction of the surface formed by cutting from the base material.

[0074] As an example of a ceramic composite having a white and transparent oxide phase that can be visually recognized by irradiation with visible light, the present invention uses a ceramic composite having a first oxide phase of (Gd 1-x ,Tb x )AlO3 phase(0 <x<1)とし、第2の酸化物相をAl2O3相とする。図8では(Gd 1-x ,Tb x )AlO3 phase is transparent and Al2O3 phase is white, and in Figure 10 (Gd 1-x ,Tb x ) shows a ceramic composite in which the AlO3 phase is white and the Al2O3 phase is transparent. 1-x ,Tb x ) The AlO3 phase is both a perovskite phase and an oxide phase.

[0075] Such a eutectic of (Gd 1-x , Tb x )AlO3 phase and Al2O3 phase is realized in a ceramic composite manufactured from raw material powders containing aluminum oxide (Al2O3), gadolinium oxide (Gd2O3), and terbium oxide (Tb4O7). That is, by activating Gd and Tb in the other oxide phase other than the Al2O3 phase, a white or transparent oxide phase can be visually recognized upon irradiation with visible light.

[0076] Next, photographs of the observation results of irradiating the ceramic composites in Fig. 8 with ultraviolet light having a wavelength of 315 nm or more and less than 380 nm (so-called black light) are shown in Fig. 9. The order of arrangement of the ceramic composites in Figs. 8 and 9 corresponds to each other. Further, photographs of the observation results of irradiating the ceramic composites in Fig. 10 with ultraviolet light having a wavelength of 315 nm or more and less than 380 nm are shown in Fig. 11. The order of arrangement of the ceramic composites in Figs. 10 and 11 corresponds to each other.

[0077] In each of the ceramic composites in Fig. 9 or Fig. 11, two oxide phases emit colored light due to the irradiation with the ultraviolet light. However, to describe in detail, when irradiated with ultraviolet light, it is divided into an oxide phase that is visually recognized as emitting light relatively brightly with a whitish tint and an oxide phase that is visually recognized as emitting light relatively darkly with a darkish tint. Thus, although both of the two oxide phases emit colored light due to the irradiation with ultraviolet light, there are differences in the emission states visually recognized.

[0078] In each of the ceramic composites in Fig. 9, the first oxide phase ((Gd 1-x , Tb x )AlO3 phase) that was visually recognized as transparent upon irradiation with visible light is visually recognized with the naked eye as emitting light relatively brightly with a whitish tint. On the other hand, the Al2O3 phase, which is the second oxide phase, is visually recognized as emitting light relatively darkly with a darkish tint.

[0079] In each of the ceramic composites in Fig. 11, the first oxide phase ((Gd 1-x , Tb xThe first oxide phase, AlO3, is visually recognized as emitting a whitish, relatively bright, colored light, while the second oxide phase, Al2O3, is visually recognized as emitting a dark, relatively dark, colored light.

[0080] As shown in Figures 8 to 11, it was confirmed that the luminescence state of the oxide phase when irradiated with ultraviolet light is reversed compared to the visually recognized state when the ceramic composite is irradiated with visible light and when irradiated with ultraviolet light, depending on the cutting direction of the base material.

[0081] Also, (Gd 1-x ,Tb x The entire ceramic composite, which has a eutectic of AlO3 and Al2O3 phases, is irradiated with ultraviolet light and then transformed into a (Gd 1-x ,Tb x Both the AlO3 phase and the Al2O3 phase emit colored light with wavelengths of 493 nm to 624 nm. When emitting light, differences in the emission (particularly differences in the wavelength of the emission) are observed for each oxide phase as shown in Figure 9 or Figure 11 in the wavelength range of 493 nm to 624 nm. In Figure 9 or Figure 11, the oxide phase (Gd 1-x ,Tb x The AlO3 phase is visually recognized as pale yellow-green to dark yellow-green to pale green. On the other hand, the Al2O3 phase, which emits a relatively dark colored light, is visually recognized as dark green.

[0082] That is, when irradiated with ultraviolet light, the wavelength of the emitted color differs between the first oxide phase and the second oxide phase. Furthermore, a comparison of Figures 9 and 11 reveals that the wavelength of the emitted color also differs between the first oxide phase and the second oxide phase. Therefore, the color emitted by irradiation with ultraviolet light has multiple wavelength peaks.

[0083] The wavelength range of the emitted color (493 nm or more and 624 nm or less) can be measured using a visible spectrophotometer or the like.

[0084] Furthermore, by comparing FIGS. 8 and 10, it can be seen that the interface density of the two oxide phases presenting a lamellar structure differs depending on the cutting direction of the base material when forming the ceramic composite from the base material. The interface density of each ceramic composite shown in FIGS. 10 and 11 is higher than the interface density of each ceramic composite shown in FIGS. 8 and 9. The higher the interface density, the easier it is for light to be scattered at the interface between the two oxide phases, and light can be scattered more uniformly over the entire in-plane area per unit area, and more uniform emitted light can be obtained with a greater emission intensity.

[0085] In addition, in the production of the ceramic composite 2 by the EFG method, it is impossible to completely prevent the material of the crucible 5 from dissolving into the melt 21, and it is very difficult to make the content of Mo or W less than 1 mol·ppm. Further, when the content of Mo or W becomes large exceeding 30,000 mol·ppm, (Gd 1-x ,Tb x )AlO3 phase or the crystallinity of the Al2O3 phase deteriorates, which is not preferable. Therefore, the amount of Mo or W contained in the ceramic composite is preferably in the range of 1 mol·ppm or more and 30,000 mol·ppm or less.

[0086] Setting the content of Mo or W to 1 mol·ppm or more and 30,000 mol·ppm or less solves these problems and enables uniform scattering of light, which is most desirable. Therefore, by making the content of Mo or W contained in the ceramic composite 2 at least 1 mol·ppm or more and 30,000 mol·ppm or less, a fine lamellar structure can be formed to perform uniform light scattering and the emission intensity can be made uniform.

[0087] When a material other than Mo or W is used for the crucible 5, the melting point is low and the amount of the material of the crucible 5 dissolved into the melt 21 increases, and there is a possibility that the content of the elements derived from the crucible 5 contained in the ceramic composite 2 increases, which is not preferable. In addition, using a material with a high melting point other than Mo or W as the material constituting the crucible 5 has problems such as reactivity with the melt 21 of the raw material and formability of the crucible 5, which is not preferable. Therefore, the ceramic composite 2 is produced using the EFG method, and (Gd 1-x ,Tbx )In order to refine the lamellar structure of the AlO3 phase and the Al2O3 phase, it is important that the ceramic composite 2 contains Mo or W within the above range.

[0088] Also, a wristwatch or a nameplate can be formed by using the ceramic composite shown in FIGS. 8 to 11. With the said ceramic composite, wristwatch parts (dial, hour markers (indexes), movement frame, bezels and cases of exterior parts, back rings, etc.) can be formed.

[0089] As described above, according to the ceramic composite and its manufacturing method according to the present invention, the eutectic lamellar structure becomes visible as white and transparent in the wavelength range of visible light and can be recognized by the naked eye visually. Therefore, it is possible to realize and provide a ceramic composite in which the eutectic lamellar structure can be recognized by the naked eye visually in the wavelength range of visible light.

[0090] Furthermore, even in the light-emitting state of the ceramic composite, the eutectic lamellar structure can be recognized by the naked eye visually. Therefore, even in the light-emitting state of the ceramic composite, the eutectic lamellar structure can be utilized visually.

[0091] Furthermore, depending on the direction of cutting the ceramic composite 2 serving as the base material, it is possible to vary the lamellar structure and the interface density of the oxide phase that appear on the surface of the ceramic composite, as well as the light-emitting state during ultraviolet light irradiation.

[0092] Therefore, the decorativeness of an article (for example, a wristwatch or a nameplate, etc.) provided with such a ceramic composite can be improved. Furthermore, since a color change can be generated in the ceramic composite along with the light emission by a black light in the dark, it is suitable as an effect material or a decorative material for entertainment purposes. Or, by changing the impression day and night, it is possible to improve the decorativeness comprehensively regardless of the time.

[0093] Furthermore, since one of the two oxide phases can be made transparent, it can be used for various purposes as a kind of skeleton material, enabling a wider range of designs and further enhancing the decorative property.

[0094] Furthermore, the lamellar structure and the oxide phase randomly appear for each ceramic composite 2 serving as the base material. Therefore, the lamellar structure and the oxide phase on the surface of each ceramic composite produced from the base material also randomly appear as shown in FIGS. 8 and 10. Therefore, it becomes possible to use them for identifying the manufacturer and the owner of the application products using such ceramic composites, and to prevent imitation and improve security. In addition, added value such as so-called one-off production products can be imparted to the application products.

[0095] Also, when the ceramic composite is irradiated with ultraviolet light, the ceramic composite can emit light in a color with a wavelength of 493 nm or more and 624 nm or less. Furthermore, the emission state and emission intensity can be changed depending on the difference in emission for each oxide phase (especially the difference in emission wavelength) and the cutting direction from the base material. Therefore, it becomes possible to further improve the decorative property.

[0096] Also, the outer shape of the ceramic composite obtained by cutting, grinding, and polishing the base material is desirably plate-shaped as shown in FIGS. 8 to 11 and has at least one surface (the surface serving as the main surface). The reason is that by making the outer shape of the ceramic composite plate-shaped, the surface serving as the main surface can be made relatively large in area. Therefore, since the lamellar structure and the oxide phase can appear over the area of the surface, the decorative property, the identification of the manufacturer and the owner, and the added value such as one-off production products can be further improved with the improved visibility of the lamellar structure and the oxide phase. In order to obtain such an effect, it is desirable that both the vertical dimension and the horizontal dimension of each ceramic composite shown in FIGS. 8 to 11 are 10 mm or more.

[0097] The emission intensity from the ceramic composite is proportional to the intensity of the ultraviolet light, which is the excitation light. Also, the ultraviolet light irradiated inside the ceramic composite decreases exponentially with the thickness of the ceramic composite. Furthermore, the emission from the ceramic composite decreases due to absorption (self-absorption).

[0098] Also, ceramic composites with different cutting directions from the base material may be combined and used for application products. Since the lamellar structure and the oxide phase appear randomly in each individual ceramic composite, by adding the randomness of the combination, it is possible to further improve the added values such as the decorativeness, the identification of the manufacturer or the owner, and the one-off production product.

[0099] Note that (Gd 1-x ,Tb x ) The more preferable range of the x value of the AlO3 phase is 0.01 ≦ x ≦ 0.5. By setting x to 0.01 or more, it becomes possible to enhance the colored emission of the (Gd 1-x ,Tb x ) AlO3 phase. Also, by setting x to 0.5 or less, the formation of Tb oxide is suppressed, and it is possible to prevent the manufacturing cost of the ceramic composite from rising, which is preferable.

[0100] Examples according to the present invention will be described below, but the present invention is not limited only to the following examples.

Example

[0101] The ceramic composite of this example was produced through each manufacturing process of the above embodiment using the manufacturing apparatus by the EFG method shown in FIGS. 1 to 6. Hereinafter, descriptions overlapping with the above embodiment will be omitted or simplified, and the same drawing numbers will be used. Furthermore, parts that require new explanations will be mainly explained.

[0102] The crucible 5 was made of Mo, and a predetermined amount of raw material powder (a powder mixture containing desired amounts of aluminum oxide (Al2O3), gadolinium oxide (Gd2O3), and terbium oxide (Tb4O7)) was placed in the crucible 5, which housed the die 9, and heated to prepare a melt 21 and a melt reservoir 22.

[0103] Next, a ceramic composite seed crystal 17 was brought into contact with a melt reservoir 22 and pulled up to produce a ceramic composite 2. The produced ceramic composite 2 was used as a base material, and the ceramic composite 2 was cut, ground, and polished so that the plate surface of the base material became the surface of the ceramic composite, thereby producing two ceramic composites as shown in Figure 8. The base material for each ceramic composite in Figure 8 was a plate with a straight body length of 6.0 mm and a width of 25 mm. The hardness (Hv) of the two ceramic composites was 1200 to 1300.

[0104] Each ceramic composite in FIG. 8 had a rectangular planar shape with length and width of 20 mm, and the thickness was adjusted to 1.5 mm for the sample on the left side of FIG. 8 and 1.0 mm for the sample on the right side of FIG.

[0105] Furthermore, the ceramic composite 2, which was the base material, was cut, ground, and polished so that a cross section perpendicular to the length direction (growth direction) of the straight body portion 26 of the ceramic composite 2 would become the surface of the ceramic composite, thereby producing three ceramic composites as shown in Figure 10. The base material of each ceramic composite in Figure 10 was block-shaped. The hardness (Hv) of the three ceramic composites was 1200 to 1300.

[0106] Each ceramic composite in FIG. 10 has a rectangular planar shape measuring 16 mm long x 12 mm wide, and the thickness was adjusted to 1.0 mm for the sample in the center of FIG. 10 and 0.7 mm for the samples on the left and right of FIG.

[0107] Comparing the samples in Figures 8 and 10, it was visually confirmed that the eutectic lamellar size was larger in Figure 8 and the interface density of the oxide phase was higher in the sample in Figure 10.

[0108] The results of irradiating each of the ceramic composites of FIGS. 8 and 10 with ultraviolet light were shown in FIGS. 9 or 11, respectively.

[0109] Next, ultraviolet light (black light) having a wavelength of 365 nm or more and 375 nm or less was incident on the obtained sample to the ceramic composite 2, and the color change operation was confirmed. The ceramic composite before the black light was incident emitted visible light having a wavelength of 380 nm or more and 780 nm or less by a phosphor as shown in FIG. 8 or FIG. 10, and the two oxide phases were white or transparent.

[0110] The ceramic composite after the black light was incident emitted colored light with a wavelength of 493 nm or more and 624 nm or less as a whole as shown in FIGS. 9 or 11. (Gd 0.92 ,Tb 0.08 )AlO3 phase emitted colored light with a relatively white tint and was visually recognized as light green or dark yellow - green. On the other hand, the Al2O3 phase emitted colored light with a relatively dark tint and was visually confirmed as dark green.

[0111] Also, in the samples of FIGS. 8 and 9, the (Gd 0.92 ,Tb 0.08 )AlO3 phase that was transparent by irradiation with visible light having a wavelength of 380 nm or more and 780 nm or less emitted colored light with a relatively white tint, while in the samples of FIGS. 10 and 11, the (Gd 0.92 ,Tb 0.08 )AlO3 phase that was white by irradiation with visible light having a wavelength of 380 nm or more and 780 nm or less emitted colored light with a relatively white tint. From the above, when comparing FIGS. 9 and 11, it was confirmed that the emission state of the produced ceramic composite is reversed depending on the cutting direction with respect to the base ceramic composite.

[0112] Also, when comparing the emission intensities of the left - and right - hand samples in FIG. 9, it was confirmed that the left - hand sample with a larger thickness emitted colored light with a stronger emission intensity. Similarly, when comparing the emission intensities of the three samples in FIG. 11, it was confirmed that the central sample with a larger thickness emitted colored light with a stronger emission intensity. That is, it was confirmed that the thicker the thickness, the higher the emission intensity regarding the emission intensity.

[0113] In each of the samples in FIGS. 9 and 11, multiple wavelength peaks appeared in the colored light emission, and there were wavelength peaks at four locations near 493 nm, near 543 nm, near 590 nm, and near 624 nm.

[0114] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims.

Explanation of Reference Numerals

[0115] 1... Manufacturing apparatus 2... Ceramic composite 3... Growth container 4... Lifting container 5... Crucible 6... Crucible drive unit 7... Heater 8... Electrode 9... Die 10... Heat insulating material 11... Atmosphere gas inlet 12... Exhaust port 13... Shaft 14... Shaft drive unit 15... Gate valve 16... Substrate entrance / exit 17... Seed crystal 18... Partition plate 19... Slit 20... Opening 21... Melt 22... Melt pool 23... Notch 26... Straight body part 28... Crystal plane of seed crystal 30... Inclined surface

Claims

1. having two oxide phases in a lamellar structure, wherein the first oxide phase is a (Gd1−x, Tbx)AlO3 phase (0 < x < 1), and the second oxide phase is an Al2O3 phase, wherein upon irradiation with visible light having a wavelength of 380 nm or more and 780 nm or less, the first oxide phase is transparent and the second oxide phase is white, or upon irradiation with visible light having a wavelength of 380 nm or more and 780 nm or less, the first oxide phase is white and the second oxide phase is transparent, a ceramic composite in which the (Gd1−x, Tbx)AlO3 phase, which is the first oxide phase, emits colored light having a wavelength of 493 nm or more and 624 nm or less upon irradiation with ultraviolet light having a wavelength of 315 nm or more and less than 380 nm.

2. The ceramic composite according to Claim 1, having a plate-like outer shape and having at least one surface.

3. A wristwatch or a nameplate comprising the ceramic composite according to any one of Claims 1 to 2.

4. A step of accommodating a plurality of dies each having a slit and arranged in parallel in their longitudinal directions in a crucible, and charging a raw material containing Gd2O3, Tb4O7, and Al2O3 as a raw material of the ceramic composite into the crucible; a step of heating the crucible to melt the raw material in the crucible to prepare a melt; a step of forming a melt pool for accumulating the melt above the slit through the slit; a step of manufacturing a base material of a ceramic composite having two oxide phases in a lamellar structure, wherein the first oxide phase is a (Gd1−x, Tbx)AlO3 phase (0 < x < 1) and the second oxide phase is an Al2O3 phase, by bringing a seed crystal into contact with the melt pool and pulling up the seed crystal; further cutting the base material of the ceramic composite so that the plate surface of the base material of the ceramic composite directly becomes the surface of the ceramic composite, having two oxide phases in a lamellar structure, wherein the first oxide phase is a (Gd1−x, Tbx)AlO3 phase (0 < x < 1) and the second oxide phase is an Al2O3 phase, and wherein upon irradiation with visible light having a wavelength of 380 nm or more and 780 nm or less, the (Gd1−x, Tbx)AlO3 phase is transparent and the Al2O3 phase is white, Or, a cross-section perpendicular to the length direction of the straight body portion of the base material of the ceramic composite is cut from the base material of the ceramic composite so as to be the surface of the ceramic composite, and the first oxide phase is a (Gd1−x, Tbx)AlO3 phase (0 < x < 1), and the second oxide phase is an Al2O3 phase. The ceramic composite has a two-oxide-phase lamellar structure, and when irradiated with visible light having a wavelength of 380 nm or more and 780 nm or less, the (Gd1−x, Tbx)AlO3 phase is white and the Al2O3 phase is transparent. A method for manufacturing a ceramic composite for manufacturing a ceramic composite.

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