WO2006001225A1

WO2006001225A1 - Corundum crystal formed body

Info

Publication number: WO2006001225A1
Application number: PCT/JP2005/011115
Authority: WO
Inventors: Katsuya Teshima; Shuji Oishi
Original assignee: Dai Nippon Printing Co., Ltd.
Priority date: 2004-06-28
Filing date: 2005-06-17
Publication date: 2006-01-05
Also published as: JPWO2006001225A1

Abstract

Disclosed is a corundum crystal formed body wherein a corundum crystal is directly grown on a base. Also disclosed is a method for easily producing such a corundum crystal formed body at low cost. Specifically disclosed is a corundum crystal formed body which is characterized by comprising an alumina base and a corundum crystal formed on the alumina base.

Description

Specification

Corundum crystal former

Technical field

The present invention relates to a corundum crystal composition that can be used for, for example, a material for high hardness, a cutting material, a laser oscillation material, a standard material for measuring physical properties, jewelry, and high value-added daily necessities.

Background art

[0002] Corundum crystals are excellent in chemical resistance, wear resistance, and weather resistance, and show high electrical insulation even in high-temperature environments. Therefore, corundum crystals, instrument bearings, micro scalpels, optical switch elements, or laser oscillations are used. It is used for materials.

[0003] As a method for producing such a corundum crystal, (1) a flame melting method (Bernoulli method) in which crystal grains are grown while dropping a raw material powder of a corundum crystal in an oxygen and hydrogen flame, (2) corundum The raw material powder of the crystal is mixed with an appropriate flux and melted in a crucible, and the crystal is precipitated and grown while the solution is slowly cooled, or the solution is precipitated with a temperature gradient in the crucible and grown. Or a flux method in which crystals are precipitated and grown while the flux is evaporated (see Non-Patent Document 1 and Non-Patent Document 2), (3) The raw powder of corundum crystal is melted in a crucible, (4) A method of forming a raw powder of corundum crystals and then sintering it by heating at a high temperature for a long time in a hydrogen gas atmosphere (Patent Documents) (See 3) I can get lost.

[0004] However, these methods are mainly performed for the purpose of producing the corundum crystal itself, and almost no attempt has been made to grow the corundum crystal directly on the substrate. ,is the current situation.

[0005] For example, in the Chiyoklarsky method of (3) above, it is possible to produce crystals with high purity, and thus the obtained corundum crystals are suitably used for laser oscillation materials and the like. In this method, it is possible to fix a seed crystal on a substrate and grow a corundum crystal on the substrate using the seed crystal as a nucleus, but it is difficult to grow a corundum crystal directly on the substrate. is there. [0006] Although it is difficult to grow corundum crystals directly on a substrate, the flame melting method of (1) and the method of sintering after molding of (4) above.

[0007] On the other hand, in the flux method (2) above, it is assumed that a corundum crystal grows accidentally on the wall surface of the crucible. Therefore, it can be expected that the corundum crystal is directly grown on the substrate. In such a case, even if the corundum crystal grows on a part of the substrate, it is very difficult to form the corundum crystal in a desired part.

[0008] Furthermore, the corundum crystal obtained by the above-described method can be stuck on the substrate, but the corundum crystal is poor in adhesion between the corundum crystal and the substrate, and the corundum crystal is easily peeled off. There is.

[0009] Among corundum crystals, dark red corundum crystals to which chromium is added are generally called rubies. Since natural ruby is produced in a relatively small amount, corundum crystals that are close to natural rubies. There is a need for a method that allows the substrate to grow directly on the substrate.

Patent Document 1: Japanese Patent Application Laid-Open No. 7-277893

Patent Document 2: JP-A-6-199597

Patent Document 3: Japanese Patent Laid-Open No. 7-187760

Non-Special Reference 1: Elwell D., Man-made gemstones, Ellis Horwood Ltd., Chichester (197 9)

Non-Special Terms 2: Elwell D., Scheel H. J., Crystal growth from high-temperature solutio ns, Academic Press, London (1975)

Disclosure of the invention

Problems to be solved by the invention

[0011] The present invention has been made in view of the above problems, and a corundum crystal formed body in which a corundum crystal is directly grown on a substrate, and the corundum crystal formed body can be easily and inexpensively manufactured. The main purpose is to provide a simple manufacturing method.

Means for solving the problem

In order to achieve the above object, the present invention provides a corundum crystal formed body comprising an alumina base material and a corundum crystal formed on the alumina base material. [0013] In the corundum crystal formed body of the present invention, corundum crystals are formed directly on the alumina base material, and the corundum crystals are grown directly on the alumina base material. Unlike the case where the corundum crystal is pasted, the adhesive strength between the alumina base material and the corundum crystal is strong, and it can be used for various applications.

[0014] In the above invention, the corundum crystal may be colorless. Alternatively, in the corundum crystal, as a coloring component, at least one element selected from the group force consisting of chromium, iron, titanium, nickel, vanadium and cobalt may be added.

[0015] Further, the present invention is characterized in that the flux and the alumina base material are heated to form a corundum crystal on the alumina base material by a flattening evaporation method in which the crystal is precipitated and grown using the evaporation of the flux as a driving force. A method for producing a corundum crystal formed body is provided.

In the present invention, since the alumina base material becomes a solute, it is possible to grow a corundum crystal directly on the alumina base material, and the corundum has an extremely strong adhesive force between the alumina base material and the corundum crystal. A crystal former can be produced. In addition, in the flux evaporation method, corundum crystals may contain elements contained in the flux as impurities, and since they are close to natural corundum crystals, corundum crystals that are highly valuable as jewelry are formed. The body can be manufactured. Furthermore, since the apparatus used in the flux evaporation method is simple and the manufacturing process is simple, a high value-added corundum crystal formed body can be provided at low cost.

[0017] In the above invention, the flux preferably contains a molybdenum compound. The molybdenum compound is preferably molybdenum oxide or a compound that generates acid molybdenum by heating. Molybdenum compounds can be evaporated relatively easily and are therefore preferred as fluxes used in the flux evaporation method.

[0018] In the above invention, the flux may contain an evaporation inhibitor! /. This is because the flux evaporation rate is suppressed, and the generation of multinuclei and the crystal growth rate can be suppressed, so that high-quality corundum crystals can be obtained.

[0019] Further, in the above invention, the evaporation inhibitor is an alkali metal compound. preferable. The alkali metal compound is preferably an alkali metal oxide or a compound that generates an alkali metal oxide by heating. By using these compounds, the evaporation of the flux can be effectively suppressed, and a high-quality and thick corundum crystal can be formed on the alumina substrate.

The invention's effect

[0020] According to the present invention, since the corundum crystal can be grown directly on the alumina base material using the alumina base material as a solute by the flux evaporation method, the adhesive strength between the alumina base material and the corundum crystal is strong. There is an effect. In addition, since a corundum crystal close to natural corundum crystals can be obtained, it has the effect of high value as a jewelry.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view showing an example of a corundum crystal formed body of the present invention.

FIG. 2 is a photograph showing an example of a cross section of the corundum crystal formed body of the present invention.

FIG. 3 is a photograph showing another example of a cross section of the corundum crystal formed body of the present invention.

FIG. 4 is a diffraction diagram showing an example of an X-ray diffraction pattern of a corundum crystal in the corundum crystal formed body of the present invention.

FIG. 5 is a process chart showing an example of a method for producing a corundum crystal formed body of the present invention.

Explanation of symbols

[0022] 1… Corundum crystal formed body

2… Alumina substrate

3… Corundum crystal

4… Sample

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the corundum crystal formed body of the present invention and the production method thereof will be described in detail.

[0024] A. Corundum crystal formed body

First, the corundum crystal formed body of the present invention will be described.

The corundum crystal formed body of the present invention is formed on an alumina substrate and the alumina substrate. A corundum crystal.

[0025] The corundum crystal formed body of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a corundum crystal formed body of the present invention. As shown in FIG. 1, the corundum crystal formed body 1 of the present invention has an alumina base 2 and a corundum crystal 3 formed on the alumina base 2.

[0026] Fig. 2 and Fig. 3 show examples of photographs taken with a scanning electron microscope (manufactured by Hitachi, Ltd., S-5000) of a cross section of the corundum crystal formed body of the present invention. As can be seen from FIG. 2 and FIG. 3, the corundum crystal formed body of the present invention has nothing between the alumina substrate 2 and the corundum crystal 3, and is directly on the alumina substrate 2. Crystal 3 has grown. Therefore, the corundum crystal formed body of the present invention has an advantage that the adhesive strength between the alumina base material and the corundum crystal is different from that obtained by pasting the corundum crystal on the alumina base material, and is used for various applications. It is possible.

FIG. 3 is a photograph showing an example of a cross section of a corundum crystal formed body having a corundum crystal to which chromium is added as a coloring component.

Hereinafter, each configuration of the corundum crystal formed body will be described.

[0027] 1. Corundum crystal

First, the corundum crystal in the present invention will be described. The collandum crystal in the present invention is formed on an alumina substrate described later.

[0028] Here, the corundum crystal will be described. The corundum crystal has a random structure belonging to the trigonal system. In this corundum structure, the cation (A1) regularly occupies 2Z3 in the hexacoordinate (octahedron) position of the lattice packed almost hexagonally close, and the AIO octahedron centered on the cation (A1). However, it has a structure in which the surface is shared in part and connected in the c-axis direction.

6

[0029] Corundum (Al 2 O 3) is the most stable of the alumina polymorphs.

twenty three

Corundum crystals with a structure have a melting point of about 2050 ° C, high hardness (Mohs hardness 9), and excellent chemical resistance, wear resistance, and weather resistance. It also exhibits high electrical insulation even in high temperature environments. Because of these properties, corundum crystals are used in instrument bearings, micro knives, optical switch elements, laser oscillation materials, and the like. In addition, a part of A1 of corundum (Al 2 O 3) is replaced with Cr, Ti, Fe, etc. These crystals are generally called rubies and sapphires and are used as jewelry.

[0030] The corundum crystal used in the present invention may be colorless, or may be selected as a coloring component from a group force consisting of chromium, iron, titanium, nickel, vanadium and cobalt. At least one element is added. It may be. When the corundum crystal is added with a coloring component, the combination of elements of the coloring component is not particularly limited, for example, chromium only; nickel only; vanadium only; cobalt only; iron and titanium; nickel , Titanium and iron; chromium and nickel; chromium, nickel and iron; combinations of chromium, titanium and iron, and the like.

[0031] Here, it is known that corundum crystals have different hues depending on the type of coloring component such as chromium, iron or titanium. For example, when a coloring component is added, the color is colorless, the color added with nickel is yellow, the vanadium added is alexandrite color, the cobalt is green, iron and titanium. Blue added, nickel added, titanium and iron added yellow-green, chromium added dark red, red or pink, chromium and nickel, or chromium, nickel and iron added The one with orange is added, and the one with chrome, titanium and iron added becomes purple. In the present invention, a corundum crystal having the above hue can be obtained by combining elements as described above.

[0032] Generally, a dark red corundum crystal to which chromium is added is called ruby, and corundum crystals other than the red corundum crystal of the chrome-added basket are called sapphire. Natural ruby has a high rare value, and in the present invention, by adding chrome to the corundum crystal, a corundum crystal formed body having a red corundum crystal close to the natural corundum crystal can be obtained. Therefore, a corundum crystal formed body with high added value can be obtained.

[0033] The addition of the above elements can be confirmed by EPMA (electron beam microanalyzer), XPS (X-ray photoelectron spectroscopy), or EDX (energy dispersive X-ray analysis). .

[0034] The content of the element in the corundum crystal varies depending on the type of element. As long as the amount of corundum crystals to be colored is contained, it may be a very small amount.

[0035] The composition of the corundum crystal is not limited to the stoichiometric one, but may be deviated from the stoichiometric composition. When the corundum crystal formed body of the present invention is produced by a flux evaporation method, which is preferably produced by a flux evaporation method as described later, the element contained in the flux is contained as an impurity in the corundum crystal. There are powers. The content of impurities in the corundum crystal is usually a very small amount of lmol% or less.

Here, the corundum crystal can be identified using an X-ray diffractometer. In this case, trigonal system, a = 4.759A, c = 12.993A, and compare with JCPDS No. 46-1212. An example of an X-ray diffraction pattern of a corundum crystal obtained by adding chromium as a coloring component in the present invention is shown in FIG. 4 (a). Figure 4 (a) shows the X-ray diffraction pattern measured by grinding to identify corundum crystals. Fig. 4 (b) is the X-ray diffraction pattern of CPDS No. 46-1212. The X-ray diffraction patterns of Figs. 4 (a) and 4 (b) were measured using CuKo; lines.

[0037] In the present invention, the corundum crystal formed body is preferably produced by a flux evaporation method! /. This is because a corundum crystal can be formed using an alumina base material described later as a solute, and a corundum crystal can be formed directly on the alumina base material. In addition, since corundum crystals obtained by the flux evaporation method may contain elements contained in the flux as impurities, they can be made into crystals containing impurities in the same way as natural corundum crystals. This is because it has the advantage of high value. Furthermore, the equipment used in the flux evaporation method is simple as long as it has a high-temperature furnace, and corundum crystals can be obtained easily.

It should be noted that a corundum crystal forming method such as a flux evaporation method is described in the section “B. Method for manufacturing corundum crystal formed body”, which will be described later.

[0039] In the present invention, the corundum crystal may intentionally contain impurities. As described above, by containing impurities, it can be made close to nature, and it has a great value as a jewelery product. [0040] The corundum crystal may be formed on the entire surface of an alumina base material to be described later, or may be formed on a part thereof. The formation position of such a corundum crystal is appropriately selected according to the use of the corundum crystal formed body of the present invention.

[0041] 2. Alumina substrate

Next, the alumina base material used in the present invention will be described. In the present invention, an alumina substrate may be used alone, or an alumina substrate and a substrate may be laminated and used.

[0042] Such an alumina base material is not particularly limited as long as it is mainly composed of alumina, but the content of impurities with respect to alumina in the alumina base material is 5% or less. Is preferable, and it is preferably 1% or less. If the content of impurities relative to alumina is too high, there is a high possibility that impurities will be eluted when corundum crystals are formed, and this may lead to the possibility that crystallization of corundum crystals may be hindered. . Examples of such impurities include general ones such as SiO,

2

Na 0, Fe 2 O, CaO, MgO, K 2 O, etc.

2 2 3 2

[0043] In the present invention, when the alumina base material and the base material are laminated, the base material to be used is not particularly limited as long as it can form an alumina base material and does not adversely affect the formation of corundum crystals. Although not limited, it is preferable that it can withstand the maximum holding temperature described in the heating / evaporation process section of “B. Corundum crystal forming body” described later. Examples of such a substrate include platinum, sapphire, alumina silica, silicon carbide, and alumina. Since the alumina substrate is not required to have a low impurity content and high purity, unlike the alumina substrate, it may be of low purity.

[0044] In the above case, the alumina substrate may be partially formed or may be formed on the entire surface of the substrate, but may be partially formed. In this case, platinum is used as the substrate. It is preferable to use it. When a substrate made of alumina is partially formed on a substrate other than platinum, when forming a corundum crystal, part of the substrate may elute and adversely affect the formation of the corundum crystal. Because. In addition, platinum is considered to have no effect on the formation of corundum crystals with low reactivity with alumina. [0045] When an alumina substrate is partially formed on a platinum substrate, corundum crystals are formed on the alumina substrate, and on the platinum substrate on which no alumina substrate is formed. It is preferable that no corundum crystal is formed. This is because a corundum crystal formed body in which a corundum crystal is formed only in a desired portion can be obtained. Furthermore, this is because a corundum crystal formed body having a corundum crystal formed in a pattern can be obtained by forming an alumina substrate in a pattern on a platinum substrate.

[0046] In addition to the above, when the platinum layer is formed in a pattern on the alumina base, or the alumina base and the platinum layer are formed in a pattern on the base. Also in this case, a corundum crystal formed body having a nodular corundum crystal can be obtained.

[0047] Examples of the method for forming the alumina substrate on the substrate include a physical vapor phase method such as a sputtering method and an electron beam (EB) method, an electrolysis method, and a compression molding method.

[0048] Examples of the method for forming the platinum layer include general physical vapor phase methods such as sputtering, ion plating, and vacuum deposition.

In the present invention, when a corundum crystal is formed by a flux evaporation method described later, the alumina base material becomes a raw material for the corundum crystal, and the corundum crystal is formed by elution of the alumina from the alumina base material. Therefore, the thickness and size of the alumina base material can maintain the shape of the alumina base material even after the alumina is eluted from the alumina base material when the corundum crystal is formed using the flux evaporation method. The thickness and size are not particularly limited, and may be appropriately selected according to the use of the corundum crystal formed body of the present invention.

[0050] The shape of the alumina substrate used in the present invention is not particularly limited, and is appropriately selected depending on the use of the corundum crystal formed body. For example, containers such as crucibles, plate shapes, rod shapes, wire shapes, ring shapes, cube shapes, uneven shapes, spherical shapes, three-dimensional shapes, cone shapes (cones, pyramids, etc.), column shapes (columns, prisms, etc.), and the like can be mentioned. Also, for example, the inside of the mesh nail may be hollow.

[0051] B. Method for producing corundum crystal formed body Next, the manufacturing method of the corundum crystal formed body of the present invention will be described. The method for producing a corundum crystal formed body of the present invention forms a corundum crystal on an alumina base material by heating the flux and the alumina base material by a flux evaporation method in which the crystal is precipitated and grown using the evaporation of the flux as a driving force. It is characterized by this.

[0052] The flux method is a kind of solution method and is also called a flux method. When growing a crystal by the flux method, an appropriate salt or oxide that becomes a flux and a raw material that becomes a solute are mixed, heated and melted, and then the solution is gradually cooled or the flux is evaporated. Create a supersaturated state and grow crystals. Depending on the difference in formation method of this supersaturated state, it is roughly divided into a flux evaporation method, a flux slow cooling method and a flux temperature gradient method.

[0053] The present invention uses the flux evaporation method among the above. The flux evaporation method is a method that promotes nucleation and crystal growth using evaporation of flux as a driving force. For example, as shown in Fig. 5 (a), an alumina substrate filled with a sample 4 containing flux is used. The crucible 2 is placed in the high-temperature furnace 12, heated to evaporate the flux in the sample 4, and the corundum crystal 3 is deposited and grown on the inner wall of the crucible, which is the alumina substrate 2. 5 (b)), corundum crystal formed body 1 is obtained (Fig. 5 (c)).

[0054] Here, the mechanism by which corundum crystals are formed on the alumina substrate is considered as follows. In other words, the alumina base material becomes a solute, and the surface force of the alumina base material gradually elutes due to the heating of the flux and the alumina base material, and supersaturation occurs at the interface between the portion of the alumina base material where the alumina is dissolved and the flux that evaporates. Since a state is created, it is assumed that corundum crystals precipitate on the surface of the alumina substrate and grow.

[0055] In this way, corundum crystals are considered to precipitate and grow on the portion of the alumina base material where the alumina elutes and the flux that evaporates. Thus, for example, as shown in FIG. When the crucible which is the base material 2 is filled with the sample 4 containing the flux, as shown in Fig. 5 (b), the portion of the alumina base material 2 where the alumina is eluted during the formation of the corundum crystal and the sample 4 evaporates. Since the corundum crystal 3 is formed at the portion that becomes the interface A with the flux, it is considered that a corundum crystal formed body 1 as shown in FIG. 5 (c) is obtained.

[0056] Thus, in the present invention, it is possible to grow corundum crystals directly on an alumina substrate by using the alumina substrate as a solute. Also, conventional flux Compared with the melting of the alumina powder used in the process, the rate at which the alumina substrate strength alumina elutes is slow, so the generation of polynuclears and the crystal growth rate can be suppressed, and high-quality corundum crystals can be produced. Obtainable. Furthermore, since the corundum crystals are precipitated and grown as described above using the alumina base material as a solute as described above, there is an advantage that a corundum crystal formed body having a very strong adhesive force between the alumina base material and the corundum crystals is obtained.

[0057] Here, when there is a large amount of alumina eluted from the alumina base material, there is a concern that the shape of the alumina base material may change. For example, a crucible made of alumina that can be used as an alumina base material is alumina. It is a compression-molded powder of V and has a certain degree of heat resistance, so that a large amount of alumina does not elute easily. Therefore, in the present invention, the amount of elution of alumina from the alumina base material is maintained on the alumina base material while maintaining the shape of the alumina base material so as not to change the shape of the alumina base material. Collandum crystals can be formed.

[0058] Further, since the corundum crystals are formed even if the amount of alumina eluted from the alumina base material is small, the amount of alumina eluted may be small.

[0059] Further, in the present invention, since the flux evaporation method is used, the corundum crystal may contain an element contained in the flux as an impurity, and a product close to natural corundum crystal is obtained. It is possible to produce a corundum crystal formed body having a high value.

[0060] In addition, as shown in Fig. 5 (a), the apparatus used for the flux evaporation method is simple if it has a high-temperature furnace 12, and as described above, the flux is evaporated to precipitate and grow crystals. Since a corundum crystal can be obtained, the production process is simple, and a high-value-added corundum crystal can be produced at low cost.

[0061] The method for producing a corundum crystal formed body of the present invention comprises a sample preparation step for preparing a sample containing a flux, heating the sample and the alumina substrate, and further maintaining the temperature at a high temperature to evaporate the flux. A heating 'evaporation step for depositing and growing corundum crystals on an alumina substrate, a cooling step for cooling the sample heated in the heating'evaporation step, and a sample remaining after the caloric heat-evaporation step and the cooling step. And a separation step of separating the collandum crystal-former by dissolving them in a suitable medium. Hereinafter, each step of the manufacturing method of such a corundum crystal formed body will be described.

[0062] 1. Sample preparation process

In the method for producing a corundum crystal formed body of the present invention, a sample preparation step for preparing a sample containing a flux is first performed.

[0063] The sample used in the present invention is not particularly limited as long as it contains a flux, and may contain a force coloring additive. When sample strength S flux is contained, colorless corundum crystals can be formed, and when flux and coloring additives are contained, colored corundum crystals can be formed. For example, when a chromium compound is used as an additive for coloring and the sample contains a flux and a chromium compound, a red corundum crystal can be formed.

Hereinafter, the flux and coloring additives will be described.

[0064] (1) Flux

The flux used in the present invention is not particularly limited as long as it evaporates in a heating / evaporation process described later, and dissolves in an appropriate medium in a separation process described later. It is preferable to do. Molybdenum compounds can be evaporated relatively easily, and therefore are suitable as a flux used in the flux evaporation method.

[0065] As such a molybdenum compound, molybdenum oxide or a compound that generates acid molybdenum by heating in a heating and evaporation step described later can be used. Examples of the compound that generates molybdenum oxide by heating include molybdenum carbonate, molybdenum sulfate, molybdenum nitrate, molybdenum hydroxide, and hydrates thereof. In the present invention, among the above, it is preferable to use oxymolybdenum.

[0066] In the present invention, the flux may contain an evaporation inhibitor! /. This is because the evaporation rate of the flux can be suppressed and the generation of multinuclei and the crystal growth rate can be suppressed, so that a high-quality corundum crystal can be obtained. Further, as described above, the corundum crystal is precipitated and grows by forming a supersaturated state at the interface between the portion where the alumina base strength alumina is eluted and the flux that evaporates. If the evaporation rate of the flux is too high, even if a corundum crystal is deposited in a certain part of the alumina base material, it will not be in contact with the flux before it grows, and the corundum crystal may not grow any more. On the other hand, by suppressing the evaporation rate of the flux, it is possible to lengthen the time during which the alumina-eluting portion of the alumina base material is in contact with the flux. Crystals can be formed.

[0067] On the other hand, when the flux does not contain the above evaporation inhibitor, the evaporation rate of the flux is faster and the nucleation rate is faster than when the flux contains the evaporation inhibitor. A relatively thin corundum crystal can be formed on the substrate.

[0068] The evaporation inhibitor is not particularly limited as long as it can suppress the evaporation of the flux and can be dissolved in an appropriate medium in the separation step described later. Is preferably used. This is because by using an alkali metal compound, evaporation of the flux can be effectively suppressed, so that a high-quality and thick corundum crystal can be formed on the alumina substrate.

[0069] As such an alkali metal compound, an alkali metal oxide, or a compound that generates an alkali metal oxide by heating in a heating and evaporation step described later can be used. Examples of the compound that generates an alkali metal oxide by heating include alkali metal carbonate, alkali metal sulfate, alkali metal nitrate, alkali metal hydroxide, and hydrates thereof. In the present invention, among the above, Li 0, N

2 a O and K O forces Group forces Generate at least one selected alkali metal oxide

twenty two

It is preferable that Specific examples include Li CO, Na CO, and K CO.

2 3 2 3 2 3

[0070] Further, the content of the alkali metal compound is 40 mol% or less, particularly 30 mol% or less, particularly 20 mol% or less with respect to the total number of moles of alkali metal atoms of the alkali metal compound. It is preferable to contain so that it may become. In the present invention, since nucleation and crystal growth are promoted by the evaporation of flux as driving force, crystallization may be hindered if the content of alkali metal compound is too large. [0071] (2) Additive for coloring

Next, the coloring additive used in the present invention will be described. The coloring additive used in the present invention is different depending on the coloring component added to the corundum crystal as described in the above-mentioned section “A. Corundum crystal forming body”, and is appropriately selected and used. The For example, when a colorless corundum crystal is formed, a coloring additive is not necessary. Also, for example, iron and titanium are added as coloring components! In the case of forming corundum crystals, iron compounds and titanium compounds are used as coloring additives. For example, when forming a corundum crystal to which chromium is added as a coloring component, a chromium compound is used as the coloring additive, and to form a corundum crystal to which chromium and nickel are added as coloring components. As coloring additives, chromium compounds and nickel compounds are used.

The following are examples of corundum crystals of iron and titanium-added calenders and corundum crystals of chromium-added calenders.

[0072] (Corundum crystal with iron and titanium)

In the present invention, when iron and titanium are added as coloring components to form corundum crystals, iron compounds and titanium compounds are used as coloring additives.

[0073] The iron compound is not particularly limited as long as it is melted in the heating and evaporation step described later, but is preferably a compound that generates iron ions by heating. Examples of the compound that generates iron ions by heating are iron oxide, iron hydroxide, iron sulfate, iron carbonate, iron nitrate, iron chloride, iron citrate, iron phosphate, iron fluoride, iron iodide, and sulfur. Examples thereof include iron acids and hydrates thereof. Among them, it is preferable to use acid pig iron in the present invention. In this case, the iron valence in the iron oxide may be bivalent or trivalent, and bivalent and trivalent iron may be mixed.

[0074] The titanium compound is not particularly limited as long as it can be melted in the heating and evaporation process described later, but is preferably a compound that generates titanium ions by heating. Examples of the compound that generates titanium ions by the above heating include titanium oxide, nitrogen Titanium chloride, titanium tetraisopropoxide, titanium oxalate, titanium sulfate, titanium bromide, titanium chloride, and hydrates thereof. Among them, it is preferable to use acid titanium in the present invention. In this case, examples of the valence of titanium in the above-mentioned titanium oxide include divalent, trivalent and tetravalent. The valences of titanium may be single or mixed.

[0075] The addition amount of the iron compound and the titanium compound is not particularly limited as long as the addition amount is sufficient to color the corundum crystals! /.

[0076] The mixing ratio of the iron compound and the titanium compound varies depending on the valences of iron and titanium, but the weight ratio of the iron element to the titanium element is usually Fe: Ti = 1: 0. Mix until 05-20. Among them, it is preferable to mix so that 1: 0.0.07 to 15, particularly 1: 0.1. By setting the above mixing ratio within the above range, it is possible to obtain a corundum crystal colored bright blue.

[0077] (Corundum crystal of chromium-added powder)

In the present invention, when chromium is added as a coloring component to form corundum crystals, a chromium compound is used as the coloring additive.

[0078] The chromium compound is not particularly limited as long as it can be melted in the heating and evaporation step described later, but is preferably a compound that generates chromium ions by heating. Examples of the compound that generates chromium ions by the above heating include acid chrome, chromium hydroxide, chromium sulfate, chromium carbonate, chromium nitrate, and hydrates thereof. Among them, it is preferable to use acid-chromium for the present invention.

[0079] The amount of the chromium compound to be added is not particularly limited as long as the amount of corundum crystals that can be colored is added. /.

[0080] (Other corundum crystals)

In the present invention, when forming a corundum crystal to which nickel, vanadium or cobalt is added as a coloring component, a nickel compound, vanadium compound or cobalt compound may be used as a coloring additive.

[0081] The nickel-rich compound is not particularly limited as long as it can be melted in the heating and evaporation step described later, but is preferably a compound that generates nickel ions by heating. Examples of the compound that generates nickel ions by the heating include nickel acetate, nickel carbonate, nickel chloride, nickel hydroxide, nickel iodide, nickel nitrate, nickel oxide, nickel sulfamate, nickel sulfate, and hydrates thereof. Etc. Among these, it is preferable to use acid nickel. In this case, the nickel valence in the above-mentioned nickel oxide may be bivalent or trivalent, or it may be a mixture of bivalent and trivalent nickel.

[0082] The vanadium compound is not particularly limited as long as it melts in the heating and evaporation step described later, but is preferably a compound that generates vanadium ions by heating. Examples of the compound that generates vanadium ions by the above heating include vanadium carbide, vanadium chloride, vanadium oxide, vanadium oxide sulfate, vanadium oxide oxide, and hydrates thereof. Among these, it is preferable to use vanadium oxide. In this case, the valence of vanadium in the above acid vanadium includes trivalent, tetravalent and pentavalent. The valences of vanadium may be single or mixed.

[0083] Further, the cobalt compound is not particularly limited as long as it is melted in a heating and evaporation step described later, but a compound that generates a corona ion by heating is preferable. Examples of the compound that generates cobalt ions by the heating include cobalt bromide, cobalt chloride, cobalt citrate, cobalt fluoride, cobalt dalconate, cobalt hydroxide, cobalt iodide, cobalt nitrate, cobalt oxalate, Examples include cobalt oxide, cobalt phosphate, cobalt stearate, cobalt sulfate, cobalt sulfate, and hydrates thereof. Among them, in the present invention, it is preferable to use cobalt citrate, cobalt fluoride, cobalt dalconate, cobalt hydroxide, cobalt iodide, cobalt oxalate, cobalt oxide, cobalt phosphate, and cobalt stearate. In particular, it is preferable to use cobalt oxide, cobalt hydroxide, cobalt stearate, or cobalt phosphate. In this case, the cobalt valence in the above cobalt toy compound may be bivalent or trivalent, and both divalent and trivalent cobalt may be mixed! / /.

[0084] The amount of the nickel compound, vanadium compound, or cobalt compound added is not particularly limited as long as it is added in an amount sufficient to color the corundum crystals. [0085] Further, in the present invention, a corundum crystal is formed in which chromium as a coloring component and at least one element selected from the group force consisting of iron, titanium, nickel, vanadium and cobalt are added. In this case, in addition to the chromium compound described above, an iron compound, a titanium compound, a nickel compound, a vanadium compound, or a cobalt compound may be used.

[0086] At this time, the addition amount of the iron compound, titanium compound, nickel compound, vanadium compound, or cobalt compound described above is not particularly limited as long as an amount sufficient to color the corundum crystal is added. Not something! /.

In the present invention, the above-mentioned iron compound, titanium compound, chromium compound, nickel compound, vanadium compound or cobalt compound can be used in various combinations, and the mixing ratio of these compounds is as follows. It is appropriately selected according to the use of the corundum crystal formed body.

[0088] (3) Other

In preparing the sample in this step, the flux and coloring additives are usually stirred. The stirring method is not particularly limited as long as it is a method capable of stirring uniformly. For example, a method of sufficiently stirring the flux and coloring additive in a mortar can be mentioned.

[0089] In the present invention, the sample may contain impurities. This makes it possible to obtain crystals that are close to natural V, have high value as jewelry, and can form corundum crystals.

[0090] The sample may contain an aluminum compound! In the present invention, as described above, the alumina base material becomes a solute, and the surface force of the alumina elutes to form a collandum crystal. The aluminum compound is further included as the solute. You can also. In this case, the content of the aluminum compound is appropriately determined in consideration of the balance between the elution of alumina from the alumina base material and the melting of the aluminum compound so as not to prevent the precipitation and growth of corundum crystals on the alumina base material. Prepared. For example, if the content of the aluminum compound is too large, crystals may grow with the aluminum compound serving as a nucleus, and it may be difficult to form a corundum crystal on the alumina substrate. As such an aluminum compound, alumina (acid aluminum) or a compound that generates alumina by heating in a heating / evaporation process described later can be used. Examples of the compound that forms alumina by the above heating include hydroxyaluminum aluminum, aluminum sulfate, aluminum carbonate, aluminum nitrate, and hydrates thereof. In the present invention, among these, it is preferable to use alumina.

[0092] 2. Heating / evaporation process

Next, the heating and evaporation step in the present invention will be described. The heating / evaporation step in the present invention is a step of heating the sample and the alumina base material, further evaporating the flux by maintaining the temperature at a high temperature, and depositing and growing corundum crystals on the alumina base material.

[0093] In this step, for example, when a crucible having an alumina force is used as the alumina base material, the alumina base material 2 is filled with the sample 4 containing the flux as shown in FIG. 5 (a). Cover the crucible with the lid 13 and place it in the high temperature furnace 12. Next, when the temperature is raised to the maximum holding temperature and held at that temperature for a predetermined time, the flux in sample 4 evaporates, and the crucible force that is alumina substrate 2 also elutes alumina, driving the evaporation of this flux. As a force, the precipitation and growth of collandum crystal 3 is promoted (Fig. 5 (b)). As a result, a corundum crystal formed body 1 in which the collandum crystal 3 is formed on the alumina substrate 2 is produced (FIG. 5 (c)).

[0094] The maximum holding temperature in this step is not particularly limited as long as it is a temperature at which the flux evaporates, the coloring additive melts, and the alumina substrate strength alumina elutes. 950 ^{^o} C~1300 ^o C, Chudechi 975 ^{^o} C~1250 ^o C, it is preferred that within the limits of the special [this 1000 ^{^o} C~1200 ^o C.

[0095] Further, as the rate of temperature rise when setting the maximum holding temperature, a sample containing a flux and an additive for coloring, etc., and a rate capable of uniformly heating the alumina substrate are particularly effective. It is not limited. Further, the holding time at the maximum holding temperature is not particularly limited as long as it is a time during which the corundum crystal can be sufficiently grown.

[0096] Since the alumina base material is the same as that described in the above-mentioned section "A. Corundum crystal formed body", description thereof is omitted here. In the present invention, the alumina base material is a container such as a crucible in which the sample is filled, and the sample may be placed in a container that is the alumina base material. It may be placed inside. When the alumina base material and the sample are placed in a container, the container used is not particularly limited as long as it can withstand the above-mentioned maximum holding temperature and has low reactivity with the sample. Use a container that also has strength.

[0098] Further, when the sample is placed in a container that is an alumina base material, or when the alumina base material and the sample are placed in the container, the alumina base material and the sample are mutually compatible. It arrange | positions so that it may touch.

[0099] In the present invention, as described above, the alumina base material becomes a solute, and the alumina also gradually elutes the surface force of the alumina base material by heating. Since a supersaturated state is created at the interface, it is considered that corundum crystals precipitate on the surface of the alumina substrate. From this, for example, when the crucible, which is the alumina substrate 2 as shown in FIG. 5 (a), and the sample 4 containing the flux are heated, the flux evaporates, so FIG. 5 (b) As shown, the upper side force of the inner wall of the crucible which is the alumina base material 2 is assumed to gradually form the corundum crystal 3.

[0100] Further, since it is assumed that corundum crystals precipitate and grow only on the portion of the alumina base material where the alumina elutes and the flux that evaporates, it is assumed that the portion where the corundum crystals are to be formed is a flux. Is required to be completely evaporated. For example, to form corundum crystals on the inner wall and bottom surface of the crucible, which is the alumina substrate 2 as shown in Fig. 3 (a), completely evaporate the flux so that no flux remains on the bottom surface of the crucible. It is good.

[0101] 3. Cooling process

Next, the cooling process in the present invention will be described. The cooling step in the present invention is a step of cooling the sample or the like heated in the heating and evaporation step.

In this step, for example, the crucible which is the alumina base material 2 filled with the sample 4 containing the flux is taken out from the high temperature furnace 12 as shown in FIG. 5 (a) and cooled to room temperature. Examples of the cooling method include a method of allowing the crucible to cool as long as it can be cooled to room temperature. [0103] 4. Separation process

Next, the separation step in the present invention will be described. The separation step in the present invention is a step of separating the corundum crystal formed body by dissolving the sample remaining after the heating / evaporation step and the cooling step in an appropriate medium.

[0104] In the present invention, a sample such as a flux remains after the cooling step such that the flux is not completely evaporated in the heating / evaporating step, or the evaporation inhibitor remains undissolved. In this step, only the corundum crystal formed body can be easily separated by dissolving these remaining samples in an appropriate medium.

[0105] The medium used for dissolving the remaining sample is not particularly limited as long as it can dissolve the remaining sample other than the corundum crystal and the alumina base material without affecting the corundum crystal. For example, cold water, hot water, hot water and the like can be mentioned.

[0106] The corundum crystal formed by the method for producing a corundum crystal formed body of the present invention is the same as that described in the above-mentioned section "A. Corundum crystal formed body". Is omitted.

[0107] 5. Other

In the present invention, when an alumina substrate is partially formed on a white metal substrate as described in the above-mentioned section “A. Corundum crystal formed body”, the alumina substrate is formed. Corundum crystals may also be formed on an unplated platinum substrate. In such a case, when producing a corundum crystal formed body in which corundum crystals are not formed on a platinum substrate, an acid melting treatment is performed using an acid flux such as potassium hydrogen sulfate. The corundum crystals formed on the platinum substrate can be peeled off. Corundum crystals formed on the alumina base material are not peeled off by the acid melting treatment. Thereby, a corundum crystal formed body in which a corundum crystal is formed only in a desired portion can be obtained.

[0108] In addition, when the platinum layer is formed in a pattern on the alumina base material, or when the alumina base material and the platinum layer are formed in a pattern shape on the base material, the acid fusion is performed. Corundum crystals formed on the platinum layer by the treatment can be peeled off. [0109] The present invention is not limited to the above embodiment. The above-described embodiment is an example, and has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same operational effects or equivalents thereof. Anything is included in the technical scope of the present invention.

Example

[0110] Hereinafter, the present invention will be specifically described by way of examples.

[Example 1]

Iron oxide (0.004 g), titanium oxide (0.004 g), molybdenum oxide (28.5 g) and lithium carbonate (0.5 g) were weighed and placed in a mortar. This mixed sample was dry mixed in a mortar for about 20 minutes. Thereafter, the mixed sample was filled in an alumina crucible (purity 99.6%), covered, and placed in an electric furnace. The electric furnace was heated to 1100 ° C at a rate of 45 ° C per hour and held at that temperature for 5 hours. After the holding, the alumina crucible was taken out from the electric furnace and allowed to cool to room temperature. A photograph of the cross section of the obtained corundum crystal formed body is shown in FIG. As shown in FIG. 2, a corundum crystal 3 having a thickness of about 150 / zm was formed on the inner wall of the alumina crucible 2.

[0111] [Example 2]

Acid chrome (0.008 g), molybdenum oxide (28.5 g) and lithium carbonate (0.5 g) were weighed and placed in a mortar. This mixed sample was dry mixed in a mortar for about 20 minutes. Thereafter, the mixed sample was filled in an alumina crucible (purity 99.6%), covered, and placed in an electric furnace. The electric furnace was heated to 1100 ° C at a rate of 45 ° C per hour and held at that temperature for 5 hours. After the holding, the alumina crucible was taken out from the electric furnace and allowed to cool to room temperature. Fig. 2 shows a photograph of the cross section of the resulting corundum crystal formed body. As shown in FIG. 3, a red corundum crystal 3 having a thickness of about 150 m was formed on the inner wall of the alumina crucible 2.

Claims

The scope of the claims

[1] A corundum crystal formed body comprising an alumina base material and a corundum crystal formed on the alumina base material.

[2] The corundum crystal formed body according to claim 1, wherein the corundum crystal is colorless.

[3] The corundum crystal includes at least one element selected from the group consisting of chromium, iron, titanium, nickel, vanadium and cobalt as a coloring component. The corundum crystal formed body according to Item.

[4] Corundum crystal formation, characterized in that the flux and alumina substrate are heated to form a corundum crystal on the alumina substrate by the flux evaporation method in which the evaporation of the flux is used as the driving force to drive the flux. Body manufacturing method.

[5] The method for producing a corundum crystal formed body according to claim 4, wherein the flux contains a molybdenum compound.

6. The method for producing a corundum crystal forming body according to claim 5, wherein the molybdenum compound is molybdenum oxide or a compound that generates molybdenum oxide by heating.

[7] The method for producing a corundum crystal formed body according to claim 5 or 6, wherein the flux contains an evaporation inhibitor.

[8] The method for producing a corundum crystal formed body according to claim 7, wherein the evaporation inhibitor is an alkali metal compound.

[9] The method for producing a corundum crystal forming body according to claim 8, wherein the alkali metal compound is an alkali metal oxide or a compound that generates an alkali metal oxide by heating. .