JPS61103533A - Apparatus for hydrothermal synthesis - Google Patents

Abstract

PURPOSE:To enable free heating at higher temp. in a hydrothermal synthesis by housing a heating source in a high pressure chamber interposing a heat isolating material and providing an air tight casing having an inversed cup shape with closed top to the inside of the heating source. CONSTITUTION:The apparatus is constituted of a combination of an air tight casing 7 with a receiving tray 9 and, further, a heater 6 arranged around the casing 7 in a high pressure chamber 4. When hydrothermal synthesis is carried out under pressure through a pressure medium and heating with a heater 6, an aq. soln. 13 in a crucible 11 is transferred by evaporation to the top of the crucible 11, and a part of the evaporated water is transferred to the bottom of the crucible along the inside surface of the air tight casing 7 by the effect of convection due to the temp. difference at the top and the bottom of the crucible (the top is at higher temp. and the bottom is at lower temp.). Since, in the case, the bottom part is in a lower temp. zone, evaporated water arriving at the bottom part is coagulated supporting the foot end of the casing 7 and stored in a receiving tray 9 around the foot end of the casing 7.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is aimed at improving the internal structure of a hydrothermal synthesis device used for manufacturing quartz crystal for piezoelectric materials and hydrothermal treatment of various minerals. It is intended to eliminate contamination, raise the heating temperature, and enable repeated use of reaction members.

(Prior art) A hydrothermal synthesis device is a device for carrying out a hydrothermal synthesis method on an industrial scale, and the hydrothermal synthesis method is a book related to the well-known publication "High Pressure Experimental Technology and Its Applications". (edited by the High Pressure Subcommittee of the Japan Society of Materials Science, published by Maruzen Co., Ltd., published on September 20, 1962), pages 729 to 742, By increasing the solubility of the agent and increasing the reaction rate, hydrothermal growth can be used to obtain single crystals of compounds that are difficult to dissolve in water or solvents at normal pressure and below the boiling point, or by hydrothermal treatment of natural minerals and synthetic crystals to remove impurities. In a broad sense, it includes hydrothermal treatment for extraction and removal of strain, as well as hydrothermal metamorphism in which minerals are hydrothermally treated with an aqueous solution and transformed into different minerals.
The apparatus for carrying out such hydrothermal synthesis is shown in Figures 11-19 on page 730 of the same book, and Figures 11 and 2 on page 737 of the same book.
4, and if the description in the same book is adapted for FIGS. 11 and 19, it will be as follows. That is, in the attached FIG. 2, a temperature difference is created between the upper and lower parts of the reaction vessel 22 in the apparatus main body 21, and the base material 23 is placed at the bottom where the temperature is higher.
The frame with the seed crystal 24 suspended thereon is placed in the upper part where the temperature is low, and a perforated metal disk 25 is placed between the two to maintain a uniform temperature in each part of the upper and lower parts. The amount of solvent necessary to raise the internal pressure is added, the lid 26 of the container is closed, and the container 22 is heated to increase the temperature and pressure inside the container 22. When the reaction temperature is reached, the base material 23 will dissolve, and the solution at the bottom will become saturated.Since the temperature at the top of the container is lower than that at the bottom, the solution at that part will become supersaturated, and the seed crystals 2
In the example shown in Figure 4 above, crystal growth begins, and due to the temperature difference between the top and bottom, convection occurs within the container and the solution circulates, so crystal growth continues. The figure shows, of course, the case of hydrothermal synthesis of crystal by hydrothermal growth.

(Problems to be Solved by the Invention) In conventional hydrothermal synthesis apparatuses, when performing hydrothermal synthesis in a pressurized atmosphere, most of them adopt an external heating method in which heating is performed from outside the apparatus. The heating temperature can only be used at a maximum of several hundred degrees ("C"), which limits its range of use.Also, a method is used in which liquids such as solvents in the reaction vessel are sealed in capsules, and in the capsule method, each Since it is disposable, there is a problem in that the manufacturing cost is extremely high.

(Means for Solving the Problems) The present invention solves the problems in conventional devices, uses an internal heating method in the reaction vessel as a heating method, lifts the maximum temperature limit, and uses liquid evaporation as an internal heating source. It has an internal structure that reliably prevents contamination due to convection, etc., and allows the crucible containing the material to be synthesized to be used repeatedly.
Specifically, in a high-pressure container that can be opened and closed by upper and lower lids, a heating source is built into the high-pressure chamber via a heat insulating material, and an inverted cup-shaped airtight casing with a closed top is placed inside the heating source. A pressure medium passage is opened in the lower part of the casing, and the lower end of the casing is supported by the bottom of the saucer in a saucer disposed on the lower lid.

(Function) According to the technical means of the present invention, as shown in FIG. 4
A heater 6 is installed as a built-in heating source through a heat insulating material 5 inside the
is disposed inside the heater 6, and an inverted cup-shaped airtight casing 7 whose top part 7a is closed and whose lower end 7b is open is disposed, and a pressure medium passage 8 is provided on the lower peripheral side of the casing 7.
At the same time, the lower end 7b of the casing 7 is supported on the bottom of the saucer 9 inside the peripheral edge 9a of the saucer 9 placed on the lower lid 3, and the hearth 10 is placed inside the airtight casing 7. The crucible 11 is positioned through the crucible 11, the seed crystal 17 is suspended using the top 7a of the airtight casing 7, and an aqueous solution (for example, titanium oxide, etc.) is placed in the crucible 11.
13 and is supplied to the high-pressure chamber 4 of the high-pressure vessel 1 by flowing a pressure medium (for example, argon gas, etc.) into the airtight casing 7 through the pressure medium passage 8, thereby creating an even high-pressure atmosphere inside and outside the casing. The hydrothermal synthesis is carried out through heating by the heater 6. That is, according to the present invention, the combination of the airtight casing 7 and the saucer 9 as well as the high pressure chamber 4
Due to the configuration in which the heater 6 is disposed surrounding the casing 7, when hydrothermal synthesis is performed while the pressure medium is pressurized and heated by the heater 6, the aqueous solution 13 in the crucible 11 evaporates and moves above the crucible. Some of the evaporated moisture moves downward along the inner surface of the airtight casing 7 through convection due to the vertical temperature difference (the upper part is a high temperature part and the lower part is a low temperature part), but since the lower part is a low temperature region, it reaches The evaporated water solidifies and is stored in a saucer 9 that supports and surrounds the lower end of the casing 7.

will be done. At this time, the upper part of the casing 7, that is, the top 7a side, is a high temperature part and is completely airtight, so that no evaporated moisture flows out of the casing.
In addition, there is no risk of equipment components such as the insulator 12 supporting the heater being contaminated by evaporated moisture, and are completely protected.At the same time, since the heater 6 is an internal heating method, the heating temperature is several hundred degrees Celsius compared to the conventional method. For example, heating to 2000° C. is easily possible. Also, unlike the capsule method, the opened crucible 11 can be easily used repeatedly by opening the upper and lower lids 2.3 and taking out the airtight casing 7.

EXAMPLE A suitable example of the invention is illustrated with reference to FIG. The high-pressure container 1, which is the main body of the device, the upper lid 2, which is sealed so that it can be opened and closed freely, and the lower lid 3, may be the same as those of the conventional model.
A saucer 9 with an upright peripheral edge 9a having an inner diameter slightly larger than the outer diameter of the lower end 7b of the airtight casing 7 is placed above the saucer 9, and the top 7a of the saucer 9 is closed and the lower end 7b is open. The lower end 7b of the airtight casing 7 made of metal or the like is the peripheral edge 9.
It is placed and supported in a manner such that it is supported on the bottom of the saucer 9.

A pressure medium passage 8 is bored in the lower circumferential side of the airtight casing 7, and a pelvis 14 is provided in a projecting manner on the circumferential side above the pressure medium passage 8, and using this pelvis 14, as shown in the figure,
A heat insulating material 5 having the same shape as the casing 7 is erected, and furthermore, insulators 12 and 12 are attached above and below the outer peripheral surface of the casing 7, and a heater 6 as an internal heating source is attached. When placing the crucible 11 and hearth 10 in the airtight casing 7, a saucer 9 is used as shown in the figure, and the hearth 10 is placed on a stand 15 provided on the bottom of the saucer 9. , this hearth 1
By placing the crucible 11 on 0, the crucible 11 can be easily taken out. Also, as shown in the figure, the peripheral edge 9 of the saucer 9
A seal packing 16 can also be interposed between the outer peripheral surface of the lower end 7b of the casing 7 and the corresponding outer peripheral surface of the lower end 7b of the casing 7,
This completely prevents the coagulated moisture accumulated in the saucer 9 from escaping.

(Effects of the Invention) According to the present invention, when performing hydrothermal synthesis under a pressurized atmosphere, compared to a method in which heating is performed from outside the apparatus, the configuration of the airtight casing 7 and the saucer 9 allows the high pressure chamber 4 to By disposing the heater 6 outside the casing and installing the reaction crucibles 11 through the hearth 10 inside the casing, the restriction on heating temperature is lifted and higher temperatures can be freely achieved. This means that heating can be obtained and the scope of application of hydrothermal synthesis can be expanded. At this time, the solidified moisture generated in the low temperature part (lower part) due to the convection of evaporated moisture is stored in the saucer 9, and the convection occurs along the inner surface of the casing, so the heater 6, which is a built-in heating source,
The mounting of the insulator 12 can maintain stable heating conditions without the risk of contaminating components such as the insulator 12 with evaporated moisture, and unlike the capsule type, the open crucible 11 can be used, so the crucible 11 can be used repeatedly. This makes it extremely cost-effective. In addition, necessary components such as the heat insulating material 5 and the heater 6 can be constructed compactly by using the airtight casing 7, simplifying the necessary structure, and making it extremely easy to move in and out of the high-pressure vessel, making handling convenient.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of an embodiment of the apparatus of the present invention, and FIG. 2 is a schematic diagram of a hydrothermal synthesis apparatus for producing quartz crystal. 1-High pressure container, 2-Upper lid, 3--Lower lid, 4--High pressure chamber, 5--Insulating material, 6-Tanabata, 7--Airtight casing, 8-Pressure medium passage, 9 -・Saucer, 10・---hearth,
11- Crucible, 13- Aqueous solution, 17... Seed crystal. Patent applicant: Kobe Steel, Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a high-pressure container that can be opened and closed by upper and lower lids, a heating source is built into the high-pressure chamber via a heat insulating material, and an inverted cup-shaped container with a closed top is placed inside the heating source. A hydrothermal synthesis apparatus characterized in that an airtight casing is disposed, a pressure medium passage is opened in the lower part of the casing, and the lower end of the casing is supported by the bottom of the saucer in a saucer disposed on the lower lid. 2. The hydrothermal synthesis apparatus according to claim 1, characterized in that a seal packing is interposed between the outer circumferential surface of the lower end of the airtight casing and the inner circumferential surface of the saucer surrounding it.