KR20150134060A - Method and apparatus for heat-treating low grade natural sapphire for improving quality - Google Patents

Abstract

The present invention relates to a heat treatment apparatus and a method for improving quality of low rade natural sapphire. The heat treatment method for improving the quality of low grade natural sapphire comprises: a step of performing a vacuum heat treatment while being maintained 1 minute to 10 hours after heating gemstone of the low grade natural sapphire at a 1800 to 2000°C temperature; a step of performing a first cooling process which cools the vacuum heat treated natural sapphire gemstone to the room temperature by slowly or rapidly cooling; a step of performing oxygen heat treatment while being maintained 30 minute to 5 hours after heating the natural sapphire gemstone that the first cooling process is performed at a 1700 to 1800°C temperature; and a step of performing a second cooling which cools the oxygen heat treated natural sapphire gemstone to the room temperature.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for improving the quality of low-grade natural sapphire,

The present invention relates to a heat treatment for improving the quality of low grade natural sapphire, and more particularly, to a method for improving the quality of low grade natural sapphire by performing a two step heat treatment process of vacuum heat treatment and oxygen atmosphere heat treatment, To a method and an apparatus for heat treatment for improving the quality of low-grade natural sapphire capable of improving transparency and eliminating the blackening phenomenon.

In general, sapphire is a type of ore belonging to corundum (Corundum), such as ruby, which is composed of aluminum oxide (Al ₂ O ₃ ). The blue color of sapphire contains Ti and Fe components.

In other words, sapphire is basically Al ₂ O ₃ crystal with a slightly distorted octahedral structure, and the natural high-priced blue sapphire for gemstone is blue-colored due to the incorporation of Fe and Ti impurities.

All the Fe and Ti ions present as this impurity can be replaced with aluminum cations in the lattice structure. Iron may be present as Fe ₂ O ₃ , FeO, Fe ₃ +, Fe 2 +, respectively, and Ti is usually TiO ₂ and exists as Ti ₄ + in alumina crystals. If the Fe2 + and Ti4 + ions are located in the proper place by substituting the corundum of Al3 +, the two cations interact with each other to exchange surplus and deficient electrons.

Korean Patent Laid-Open Publication No. 2014-0055433 discloses a method for manufacturing a sapphire single crystal, comprising: charging a sapphire single crystal into a chamber; Heating the inside of the chamber to raise the temperature to a target temperature; Maintaining the temperature in the chamber at a constant temperature; And cooling the inside of the chamber to room temperature, wherein the step of raising the temperature includes a first raising temperature step of raising the temperature to a first set temperature or lower at a rate of temperature increase of 4 ° C / min to 5 ° C / min, And a second heating step of heating the sapphire single crystal to a second set temperature at a heating rate of 1 DEG C / min or less when the temperature rising step is completed, thereby removing residual stress in the sapphire single crystal, The occurrence can be suppressed and the quality can be improved.

However, in Korean Patent Laid-Open Publication No. 2014-0055433, a sapphire single crystal is a heat treatment process capable of minimizing the influence of heat, and when this heat treatment process is applied to a natural sapphire stone, a blackening phenomenon occurs in the heat treated natural sapphire stone There is a problem that the quality as a jewel is lowered.

Accordingly, the present inventors have continued to study techniques for improving the quality of natural sapphire ores to improve the color or transparency by performing a vacuum heat treatment process and an oxygen atmosphere heat treatment process on low-grade natural sapphire ores, The present invention has been completed in a more economical, usable and competitive manner.

Korean Patent Publication No. 2014-0055433

An object of the present invention is to provide a method and an apparatus for heat treatment for improving the quality of low-grade natural sapphire, which can improve the color or transparency by performing a cooling process of quenching or quenching after a high-temperature heat treatment.

Another object of the present invention is to provide a heat treatment method and apparatus for improving the quality of low-grade natural sapphire capable of removing the blackening phenomenon of sapphire ores by a two step heat treatment process in which a vacuum heat treatment and an oxygen atmosphere heat treatment are sequentially performed .

In order to achieve the above-mentioned object, an embodiment of the present invention is characterized by comprising: a chamber;

A refractory mounted on an inner wall of the chamber to insulate the interior of the chamber and provided with a passage;

Crucible with low-grade natural sapphire stone;

A transfer unit for transferring the crucible from the refractory to the inside of the refractory through the passage; And

And a heating element disposed inside the refractory to emit heat for heat treatment of the low-grade natural sapphire ore. The present invention also provides a heat treatment apparatus for improving the quality of low-grade natural sapphire.

In the present invention, the conveying portion includes a plate to which the crucible is mounted, and a conveyable plate. When the crucible is transferred to the refractory center portion by the conveyance portion, the plate is brought into close contact with a side edge of the refractory, And an intercepting refractory for shielding the passage at the time when the crucible is transferred to the outside of the refractory by the conveying unit.

In the present invention, a cooling water flow path is further formed in the plate, a cooling water flow path communicated with the cooling water flow path is provided, and a cooling water flow pipe connected to the plate is further included.

According to another embodiment of the present invention, there is provided a method of manufacturing a sapphire substrate, the method comprising: heating a low-grade natural sapphire ore to a temperature of 1800 to 2000 ° C, holding the sapphire raw material for 1 minute to 10 hours,

Performing a first cooling step of cooling or quenching the vacuum heat-treated sapphire ore to room temperature;

Heating the natural sapphire ore having been subjected to the first cooling step to a temperature of 1700 to 1800 ° C and holding the natural sapphire ore for 30 minutes to 5 hours to perform an oxygen atmosphere heat treatment; And

And performing a second cooling step of cooling the natural sapphire ores that have been heat treated in an oxygen atmosphere to room temperature.

In the present invention, the slow cooling is a cold cooling.

In the present invention, the quenching cooling rate is 200 to 1000 ° C / min.

As described above, in the present invention, a vacuum heat treatment process including a temperature raising step, a temperature raising state holding step, and a cooling step of cooling or quenching low-grade natural sapphire ores is performed to improve the color or transparency of natural sapphire ores, There is an advantage that quality of natural sapphire stone can be improved.

In the present invention, it is possible to remove the blackening phenomenon of low-grade natural sapphire ores by performing a heat treatment process of a low-grade natural sapphire ore in an oxygen atmosphere and then performing a heat treatment process in an oxygen atmosphere.

According to the present invention, the crucible charged with the natural sapphire ore having been subjected to the vacuum heat treatment process is quickly transferred to the outside of the refractory, and the low-grade natural sapphire ore can be rapidly cooled.

In the present invention, the crucible loaded with the natural sapphire ore having been subjected to the vacuum heat treatment process is transferred to the outside of the refractory, and the inside and outside of the refractory are shielded to increase the quenching rate of the natural sapphire ore to improve the transparency of the natural sapphire ore.

FIG. 1 is a flowchart of a heat treatment method for improving the quality of low-grade natural sapphire according to the first embodiment of the present invention,
2 is a flowchart of a heat treatment method for improving the quality of low-grade natural sapphire according to the second embodiment of the present invention,
3 is a photograph for explaining the blackening phenomenon generated in the natural sapphire ores processed by heat according to the present invention,
FIGS. 4A and 4B are graphs of XPS results of the portions A and B with respect to the natural sapphire ore after the heat treatment in FIG. 3,
FIG. 5 is a schematic view for explaining an exemplary structure of an apparatus for implementing a heat treatment method for improving the quality of low-grade natural sapphire according to the first embodiment of the present invention,
FIG. 6 is a schematic view for explaining an exemplary structure of an apparatus for implementing a heat treatment method for improving the quality of low-grade natural sapphire according to the second embodiment of the present invention,
FIG. 7 is a schematic diagram illustrating a degree of cooling of low-grade natural sapphire at a point not shielded by a refractory and a point shielded by a refractory in the heat treatment apparatus according to the present invention,
8A and 8B are photographs of a state in which color enhancement is performed in a low grade native sapphire according to the present invention,
9A and 9B are photographs showing a state in which transparency is improved in low-grade natural sapphire according to the present invention,
FIG. 10 is a graph showing the transmittance of low-grade natural sapphire before and after heat treatment according to the present invention,
11 is a view for explaining that the heat treatment method according to the present invention is formed in two steps,
Figs. 12A and 12B are photographs of a state of low-grade natural sapphire according to the present invention before and after heat treatment in an oxygen atmosphere. Fig.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In the present invention, a vacuum heat treatment process including a temperature raising process, a temperature raising process, a cooling process of a quench or quench, and a heat treatment process of an oxygen atmosphere are performed to improve the color or transparency of the low grade natural sapphire ore, So that the quality of low-grade natural sapphire ore can be improved.

FIG. 1 is a flow chart of a heat treatment method for improving the quality of low-grade natural sapphire according to the first embodiment of the present invention. FIG. 2 is a schematic view showing a heat treatment method for improving the quality of low-grade natural sapphire according to the second embodiment of the present invention Fig.

Referring to FIG. 1, in a heat treatment method for improving the quality of low grade natural sapphire according to the first embodiment of the present invention, a low grade natural sapphire ore is charged into a crucible inside a heat treatment chamber (S100) And the temperature is raised to the target temperature (S110).

Thereafter, the primary target temperature is maintained for a predetermined time at a first target temperature (S120), the primary holding process is performed, and then the primary cooling is performed to room temperature (S130).

Subsequently, the temperature is raised to the second target temperature in the atmosphere (S140), and is held for a predetermined time at the second target temperature (S150). After the second holding process, the wafer is secondarily cooled to room temperature S160).

It is preferable that the temperature raising rate of the temperature raising step (S110, S140) to the first and second target temperatures is 5 占 폚 / min or more, the first target temperature is 1800 to 2000 占 폚, the second target temperature is 1700 to 1800 占 폚 .

In the first holding step (S120), the first target temperature is maintained for 1 minute to 10 hours, more preferably 10 minutes to 10 hours, and the second holding step (S150) is performed for 30 minutes to 5 And the secondary target temperature is maintained for a period of time.

The primary cooling step (S130) and the secondary cooling step (S160) are the steps of lowering the temperature of the low-grade natural sapphire ores that have been subjected to the heat treatment to be cooled to room temperature, .

Referring to FIG. 2, a heat treatment method for improving the quality of low-grade natural sapphire according to the second embodiment of the present invention includes a step of charging a crucible with low-grade natural sapphire materials (S200) (S210), a first holding step (S220) for a predetermined time, a temperature raising step (S240) to a second target temperature in the atmosphere, a second holding step (S250) and a second cooling step (S260) Which is the same as the embodiment.

In the heat treatment method of the first embodiment, the primary cooling step (S130) is performed by squeezing the low-grade natural sapphire raw stones completed in the primary holding step. In the heat treatment method of the second embodiment, the low-grade natural sapphire stone And the primary cooling step (S230) is performed.

At this time, the cooling rate of the primary cooling step is preferably 200 to 1000 占 폚 / min.

In the quenching step of the second embodiment, the crucible charged with the low-grade natural sapphire ore having been subjected to the primary holding step (S220) is moved out of the graphite refractory material to quench the quartz, or cooling water is supplied to the flow path formed in the crucible transferring part And the crucible placed on the crucible transfer section is quenched.

In the heat treatment methods of the first and second embodiments described above, the secondary holding step (S150, S250) for performing heat treatment in an atmospheric atmosphere includes 21% oxygen in the atmosphere, and thus included in the step of heat treatment in an oxygen atmosphere. That is, in the present invention, the oxygen atmosphere heat treatment for supplying oxygen to the low-grade natural sapphire ore in order to remove the blackening phenomenon includes the heat treatment for the upper atmosphere.

Therefore, the heat treatment method of the first embodiment of the present invention can improve the color of the low-grade natural sapphire ore by performing the vacuum heat treatment at high temperature and then the quenching followed by the atmospheric heat treatment. In the heat treatment method of the second embodiment of the present invention, After the vacuum heat treatment, it is quenched and then subjected to an oxygen atmosphere heat treatment, whereby the transparency of low-grade natural sapphire ores can be improved.

In addition, the heat treatment method of the first and second embodiments of the present invention can improve the quality of low-grade natural sapphire ores by eliminating the blackening phenomenon.

That is, when natural sapphire ores are heat treated at a high temperature of 1600 DEG C or higher and in a reducing atmosphere (vacuum, Ar or the like), blackening occurs. When blackening occurs, natural sapphire is not worth as a jewel. Oxygen atmosphere heat treatment process is performed to remove blackening.

As described above, according to the present invention, it is possible to raise the color or transparency of low-grade natural sapphire ores by heating, holding, and quenching or quenching low-grade natural sapphire ores that are not blue-colored.

At this time, the lower the natural sapphire stone is the cooling rate so that the solubility is employed at a high temperature a few TiO ₂ to Al ₂ TiO ₅ + Al ₂ O was decomposed into the _three-phase without phase of TiO ₂ changes transparent Al ₂ TiO ₅ And solidifies it into an amorphous state, thereby improving the transparency of low-grade natural sapphire ores.

In order to improve the color and transparency of the low-grade natural sapphire, it is necessary to optimize the heating furnace heating furnace charging, heating, holding and cooling devices and heat treatment conditions such as atmosphere, pressure, temperature, do.

In particular, the target temperature elevation and maintenance and cooling processes are important processes that are influenced by the color and transparency of natural sapphire.

The temperature increase step is a step of raising the internal temperature to the target temperature. There was no change in the quality at the heat treatment temperature of 1800 ° C or lower. When the temperature was raised to 1800 ° C or higher, there was a change in color and transparency improvement.

The holding process is a step of maintaining the temperature at the same temperature for a predetermined time after the temperature is raised to the target temperature, and the color and transparency may be changed depending on the holding time. The heat treatment holding time is a factor of the color improvement effect of the sample in 1 minute to 10 hours or less. When the heat treatment is performed for more than 10 hours, the evaporation of the sample occurs in a large amount and becomes smaller than the sapphire before the heat treatment, and the product is no longer worth as much. Therefore, the heat treatment effect is deteriorated for a too long time, and the holding time is preferably within a range of 1 minute to 10 hours.

The cooling process is a step of lowering the temperature to room temperature. The rapid cooling system here serves as a factor for improving the transparency of low-grade natural sapphire. The cooling rate should be as low as -200 ° C / min to solidify the rutile inclusions into amorphous to improve transparency.

FIG. 3 is a photograph for explaining the blackening phenomenon generated in the natural sapphire ore processed according to the present invention, and FIGS. 4A and 4B are graphs showing the XPS results of A and B portions of natural sapphire ores after the heat treatment in FIG.

FIG. 3 is a photograph of a natural sapphire ore cut in a vacuum atmosphere of 80 mTorr or less at a heating rate of 5 DEG C / min for 1 hour at 1700 DEG C and polished to a thickness of 1 mm. And it was confirmed that the blackening did not progress to the central portion of the A portion. The XPS analysis was performed on the A portion (FIG. 4A) and the B portion (FIG. 4B), respectively, and the change was confirmed.

The binding energies of Al, C, O, F and Na are shown in the graphs of FIGS. 4A and 4B, respectively, except for C and O, which show only a slight difference within the error range.

In the case of C, 10252.3 counts / s in the part A and 9726.96 counts / s in the part B, the intensity value decreased by 5.12%. This indicates that the C of the internal heating element during the heat treatment may diffuse to the surface portion of the sapphire and blacken. However, it is found from the XPS analysis that the surface blackening phenomenon due to diffusion of C is not. Therefore, it was confirmed that surface diffusion of carbon by the carbon heating element in the vacuum heat treatment is not a big problem.

O was 12439.8count / s for part A and 11717.4count / s for part B, and the intensity value decreased by 5.8%.

Therefore, since the vacuum heat treatment is performed in a state in which oxygen is not supplied, oxygen (O) is reduced in the natural sapphire ore after the vacuum heat treatment, and the stoichiometry of the oxidizing impurities such as FeO, TiO, It was confirmed to be blackened.

As a result, in order to solve the blackening problem, in the present invention, a two-step heat treatment process is performed in which a vacuum heat treatment at a high temperature is followed by a quenching or quenching followed by an oxygen atmosphere heat treatment.

That is, in the present invention, heat treatment is performed in a high-temperature and vacuum atmosphere at 1800 to 2000 ° C sufficient for color improvement, and then heat treatment is performed under an oxygen atmosphere at 1700 ° C to 1800 ° C and a holding time for 30 minutes to 5 hours. In this case, blackening occurs in the vacuum heat treatment, but by supplying oxygen again through the heat treatment in the oxygen atmosphere, the blackening of the surface disappears and transparent sapphire can be obtained again.

FIG. 5 is a schematic view for explaining an exemplary structure of an apparatus for implementing a heat treatment method for improving the quality of low-grade natural sapphire according to the first embodiment of the present invention, and FIG. 6 is a cross- FIG. 2 is a schematic view illustrating an example of a device configuration for implementing a heat treatment method for improving the quality of low-grade natural sapphire according to the present invention.

In order to implement the heat treatment method for improving the quality of the low-grade natural sapphire according to the first and second embodiments of the present invention, various devices can be used.

In the present invention, an apparatus for implementing a heat treatment method for improving the quality of low-grade natural sapphire according to the first embodiment includes a chamber 100; A refractory (110) mounted on an inner wall of the chamber (100) to insulate the interior of the chamber (100); A crucible 120 installed inside the refractory 110 and charged with low-grade natural sapphire ore 101; And a heating element 130 installed inside the refractory 110 to emit heat for heat treatment of the natural sapphire ore 101 of low grade.

In this apparatus, the heating method of the low-grade natural sapphire stone 101 is a resistance heating method, and the refractory 110 uses a black ceramic felting. In this apparatus, the chamber 100 is located at the outermost position, and the refractory 110, the heating body 130, the crucible 120, and the low-grade natural sapphire stone 101 are positioned inward.

The low-grade natural sapphire stone 101 to be heat-treated is charged into the crucible 120 inside the chamber 100 and the chamber 100 is closed and the internal vacuum is maintained by using a vacuum pump (not shown). It is preferable to design the internal space of the apparatus so that the degree of vacuum can be set to 40 mtorr or less, the temperature can be raised to a high temperature of 1800 ° C to 2000 ° C, and the temperature can be maintained for 1 minute to 10 hours.

As shown in FIG. 6, an apparatus for implementing a heat treatment method for improving the quality of low-grade natural sapphire according to the second embodiment includes a chamber 100; A refractory (110) mounted on an inner wall of the chamber (100) to insulate the interior of the chamber (100) and having a passage (102); A crucible 120 in which low-grade natural sapphire ore 101 is loaded; A transfer unit for transferring the crucible 120 from the outside of the refractory 110 to the inside of the refractory 110 through the passage 102; And a heating element 130 disposed inside the refractory 110 to emit heat to heat the low-grade natural sapphire stone 101.

In the apparatus embodying the second embodiment the transfer part may include a plate 151 on which the crucible 120 is seated and which can be transported and the crucible 120 is connected to the refractory 110 by a transfer part, The inside of the refractory 110 and the outside of the refractory 110 are closed by bringing the plate 151 into close contact with the side edges at a time point when the crucible 120 is transferred to the outside of the refractory 110 by the conveyance unit, An intercepting refractory 131 may be further installed.

That is, a low-grade natural sapphire stone 101 is charged from the outside of the refractory 110 to the crucible 120 placed on the plate 151 of the transfer part, and the transfer part is provided with the plate 151 through the passage 102, And the intercepting refractory 131 is in close contact with the side edge of the plate 151 to block the inside and the outside of the refractory 110.

After the vacuum heat treatment process is completed, the transfer unit transfers the plate 151 to the outside of the refractory 110, and the intercepting refractory 131 is closely attached to the passage 102 to be shielded.

Therefore, in the apparatus embodying the second embodiment, after the vacuum heat treatment process is completed, the crucible 120 in which the heat treated low grade natural sapphire stone 101 is loaded is quickly transferred to the outside of the refractory 110, The natural sapphire stone 101 can be rapidly cooled.

A cooling water flow path (not shown) may be further formed inside the plate 151 and a cooling water flow pipe 152 provided with a cooling water flow path communicated with the cooling water flow path may be further connected to the plate 151 have.

The cooling water flow pipe 152 is connected to the cooling water supply unit 160 so that the cooling water supplied from the cooling water supply unit 160 is supplied to the cooling water flow path of the plate 151 through the cooling water flow pipe 152, The cooling rate of the crucible 120 placed on the crucible 120 can be adjusted more quickly.

The crucible transfer section is formed by charging the crucible 120 with the heating element 130 after charging the low-grade natural sapphire ore 101 in a region where heat emitted from the heating element 130 is not transferred, (The inside of the refractory) where the heat released from the heating body 130 is intensively transferred to the crucible 120, and then the crucible 120 is transferred to the region where the heat emitted from the heating body 130 is not transferred To rapidly cool the low-grade natural sapphire stone 101 charged in the crucible 120. [

That is, according to the present invention, when the crucible 120 is moved to the outside of the refractory 110 so that the crucible 120 can be rapidly cooled at the end of the vacuum heat treatment process, the refractory 110 is automatically shielded without further heat conduction will be.

In addition, in the present invention, when the additional quenching is required, the cooling rate can be further increased by supplying cooling water to the plate 151 in order to improve the cooling ability because the amount of elemental materials of the natural sapphire ore 101 of low grade is different.

Here, in order to measure the actual temperature of the rapid cooling, a radiating thermometer and a thermocouple may be installed in the apparatus.

Meanwhile, in order to maximize the improvement of the color and transparency of natural sapphire, the heat treatment apparatus for improving the quality of low-grade natural sapphire according to the present invention should be able to raise and maintain the temperature to a high temperature so as to enable heat treatment at 1800 to 2000 ° C.

The chamber should not be deformed by heat released from the refractory at high temperatures and should be usable in a vacuum and gas atmosphere. A dual chamber cooling with refrigerant (water, gas, etc.) is possible to prevent heat-induced deformation of the refractory. The gas may be hydrogen, nitrogen, argon, helium, or the like.

The heating element serves to heat at 1800 ° C or higher. As the heating element material, a metal system such as tungsten, molybdenum, graphite, silicon carbide, or a nonmetal system can be used.

In the present technology, it is impossible to satisfy the high temperature condition over 1800 ℃, but it is impossible in the oxygen atmosphere. Inevitably, it is necessary to use the carbon heating element in the vacuum condition, but it can be heated to the desired temperature. In the present invention, the graphite heating body can be used to heat-treat the sapphire ores in a high-temperature vacuum condition of 1800 ° C or higher.

FIG. 7 is a schematic view illustrating the degree to which low-grade natural sapphire is cooled at a point that is not shielded by the refractory and a point shielded by the refractory in the heat treatment apparatus according to the present invention.

Referring to FIG. 7, after heating from the inside of the refractory of the heat treatment apparatus to the heating body, the point (b) shielded by the refractory proceeds faster than the point (a) which is not shielded by the refractory.

That is, in order to improve the transparency of the low-grade natural sapphire in the present invention, the crucible charged with the vacuum annealed low-grade natural sapphire is moved to the point (b) shielded by the refractory material, Lt; RTI ID = 0.0 > C / min. ≪ / RTI >

FIGS. 8A and 8B are photographs of a state in which color enhancement is performed in low-grade natural sapphire according to the present invention. FIGS. 9A and 9B are photographs showing a state in which transparency is improved in low- to be.

8A was heated to 1850 DEG C at a temperature raising rate of 10 DEG C / min at room temperature in a heat treatment apparatus, held at 1850 DEG C for 5 hours, subjected to vacuum heat treatment, and then cooled. As a result, , And the reflection light was used to confirm that the low-grade natural sapphire ore was totally more blue than before the heat treatment.

9A, the temperature was raised to 1850 DEG C at a temperature raising rate of 10 DEG C / min at room temperature and maintained at 1850 DEG C for 5 hours, followed by vacuum heat treatment and cooling. As a result, As a result, it was confirmed that low-grade natural sapphire ores were improved in transparency visually as compared with the case before heat treatment as a whole.

FIG. 10 is a graph showing the transmittance of low-grade natural sapphire before and after the heat treatment according to the present invention. FIG. 11 is a view for explaining the two-step heat treatment method according to the present invention, FIG. 6 is a photograph showing a state of low-grade natural sapphire before and after the heat treatment according to the invention. FIG.

Referring to FIG. 10, UV-VIS-NIR was used to quantitatively determine the transmittance of low-grade natural sapphire before and after the heat treatment under the processing conditions of FIGS. 8 and 9 according to the present invention.

As a result of comparing the transmittance to the blue wavelength region of 480 nm without obtaining the average transmittance value of the entire region of visible light, it was confirmed that the transmittance was increased by about 10% or more after the heat treatment before the heat treatment.

Therefore, in the region of 480nm wavelength, the transmittance is improved from 1% before heat treatment to 13% after heat treatment by 12%.

As described above, in Figs. 8 and 9, the quenching or rapid quenching after heat treatment at 1850 占 폚 can improve the color or transparency of the low-grade natural sapphire ore and improve the transparency. However, after the heat treatment, The blackening phenomenon occurs. In the present invention, as shown in Fig. 11, a two-step heat treatment process is performed.

In the present invention, in the two-step heat treatment step, after the first step of heat treatment for a predetermined time in a vacuum atmosphere of 1800 to 2000 ° C. sufficient for color improvement even if the blackening is first carried out, heat treatment is performed at 1700 to 1800 ° C. for a predetermined time in an oxygen atmosphere By performing the second step, the blackening phenomenon occurring in the low-grade natural sapphire ores can be eliminated.

That is, after performing the processes of FIGS. 8 and 9, as shown in FIG. 12A, the low-grade natural sapphire ore was blackened by reflection illumination, but the temperature was raised to 1750 ° C. at a rate of 10 ° C./min, Deg.] C for 5 hours, and subjected to an annealing treatment in an oxygen atmosphere. As a result, as shown in Fig. 12 (b), blackening was removed from low-grade natural sapphire ores.

As a result, in the present invention, by supplying oxygen to the low-grade natural sapphire raw material subjected to the vacuum heat treatment through the oxygen atmosphere heat treatment, the blackening of the surface of the low-grade natural sapphire raw material disappears and the quality of color or transparency is improved, Natural sapphire gemstones.

For reference, the photographs of FIGS. 8, 9, and 12 are photographed by performing the above-described process on different natural sapphire ores.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the embodiments set forth herein. Various changes and modifications may be made by those skilled in the art.

100: Chamber 101: Low-grade natural sapphire stone
102: passage 110: refractory
120: crucible 130: heating element
131: intercepting refractory 151: plate
152: Cooling water flow pipe 160: Cooling water supply pipe

Claims (6)

chamber;
A refractory mounted on an inner wall of the chamber to insulate the interior of the chamber and provided with a passage;
Crucible with low-grade natural sapphire stone;
A transfer unit for transferring the crucible from the refractory to the inside of the refractory through the passage; And
And a heating element disposed inside the refractory to emit heat to heat the low-grade natural sapphire ore. The apparatus of claim 1, wherein the transfer unit includes a crucible and a transferable plate,
The crucible is brought into close contact with a side edge of the refractory at a time point when the crucible is transferred to the inner center of the refractory by the transfer unit to block the inside and the outside of the refractory and the time when the crucible is transferred to the outside of the refractory Further comprising an intercepting refractory for shielding the passageway. The cooling apparatus according to claim 2, wherein a cooling water flow path is further formed inside the plate,
Further comprising a cooling water flow pipe connected to the cooling water flow path and connected to the plate, and a cooling water flow pipe connected to the plate. Heating the low-grade natural sapphire ore to a temperature of 1800 to 2000 ° C, holding the sapphire raw material for 1 minute to 10 hours, and performing a vacuum heat treatment;
Performing a first cooling step of cooling or quenching the vacuum heat-treated sapphire ore to room temperature;
Heating the natural sapphire ore having been subjected to the first cooling step to a temperature of 1700 to 1800 ° C and holding the natural sapphire ore for 30 minutes to 5 hours to perform an oxygen atmosphere heat treatment; And
And performing a second cooling step of cooling the natural sapphire ores that have been heat-treated in an oxygen atmosphere to room temperature. 5. The method of claim 4, wherein the slow cooling is cooling in the furnace. The method of claim 4, wherein the quenching cooling rate is 200 to 1000 占 폚 / min.

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