RU1804344C - Method of building-up superhigh pressures - Google Patents

Abstract

The invention relates to a technique for the physical modification of a substance, in particular, it is intended to create ultrahigh pressures in the synthesis of artificial diamonds, cubic boron nitride, and allows to increase the yield of finished products. In the synthesis of superhard materials, including the placement of the starting material in the reaction chamber of a cylindrical matrix and its subsequent compression by axial movement of a step punch, the step of a smaller diameter of which is simultaneously subjected to radial compression in an annular chamber filled with plastic material, after reaching a predetermined pressure in the plastic material, the movement of the step punch is accompanied the removal of plastic material from the annular chamber, thus supporting the desired the pressure. The method allows for the creation of ultrahigh pressures to establish a dynamic relationship between the pressure in the reaction and annular chambers. 1 ill. (L C

Description

The invention relates to a technique for the physical modification of a substance, in particular, it is intended for generating ultrahigh pressures in the synthesis of artificial diamonds, cubic bar nitride (CBN) and sub-. superhard materials (STM).

The purpose of the invention is to increase the yield of finished products.

In FIG. 1 shows a general view of a device that implements the proposed method in accordance with claims 1 and 2; figure 2 is the same, according to claims 1 and 3 of the formula.

The method is as follows ..

In the reaction chamber 1, made in the lower matrix 2, is placed a substance 3 subjected to ultrahigh pressure, for example graphite. .A stepped punch passes through the upper matrix 4, the step of a larger diameter 5 of which passes tightly through the matrix 4. A smaller step

the punch 6 fits snugly into the lower die 2 and is simultaneously in the upper die. An annular chamber 7 is formed, covering a portion of the punch 6 adjacent to most of the punch 6. It fits tightly into the lower die 2 and is simultaneously located in the upper die. An annular chamber 7 is formed, covering the part of the punch 6 adjacent to the majority of the punch 5. This chamber 7 is filled with plastic material 8. In the body of the matrix 4 radial dies 9 are made uniformly spaced around the circumference. These dies communicate the annular chamber 7 with the external environment. The dies 9 are equipped with devices controlling their output section. For example, it may be adjusting nut 10.

If necessary, it is possible to provide heating of the substance 3 by any known method.

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Another implementation of the method is possible, when accumulating capacities are made in advance in the annular chamber 7. This is possible, for example, by installing a deformable element 11 in the annular chamber 7. It can be a ring, for example, of copper, in which holes 12 are made. These holes are blocked by bridges 13 from the side facing the plastic material 8, which wrinkle upon reaching set pressure and allow access to plastic material 8 in the hole 12. By varying the size of the holes, their number, shape, volume, thickness of the jumper 13, the material of the element 11 and other parameters, it is possible to provide a dynamic connection between the pressure reaction and annular chambers, control the process of creating and maintaining pressure in the reaction chamber.

When an ultrahigh pressure is created in a solid, it is placed in the reaction chamber 1, the annular chamber is filled with plastic material 8. and a step punch is introduced into matrices 2 and 4, respectively, with its parts 6 and 5. The step punch can be made integral. A force FI is applied from the press to the larger punch stage and a force F2, which prevents the material 8 from flowing out into the gap between the dies, is applied to the upper die. Dies 2 and 4 can also be made as a whole. As the plunger lowers, pressure is created in chambers 1 and 7. Until the required pressure in the annular chamber is reached, there is no outflow of material 8 from it. The material is in a closed volume 1, providing a radial compression of the punch 6. As soon as allotropic transformations in the substance 3 begin, its volume decreases and the pressure in the reaction chamber 1 begins to drop.

The punch begins to move, compressing the material 8. At the same time, the die 9 is opened and part of the material 8 flows into the environment, but the necessary radial compression of the punch is maintained, since due to the friction forces, sufficient pressure is stored in the chamber 7. If the deformation element 11 is used, then when moving the punch, the jumpers are crushed. 13 and excess plastic material 8 enters the holes 12, filling them. Thus, the necessary pressure is maintained in the reaction chamber without an excessive increase in pressure in

annular chamber. The pressure in the chamber 7 changes exponentially with the movement of the punch, if the material is not removed from it.

Example. A device has been manufactured for implementing this method, similar to that shown in FIG. 1,

The synthesized substance is a mixture of graphite-like boron nitride with MDVa. Graphite-like boron nitride was used as a plastic material. The volume of the reaction chamber is 6.3 cm; annular chamber 11.7 cm. After loading the substances and installing the punch on the press

D0137A an ultrahigh pressure of 6.0 hPa was created. After heating to a temperature of 1900 ° С, synthesis was carried out for 60 s. The output of crystals of cubic boron nitride averaged 170 ... 180 carats, the crystal size - 30 ... 100 microns. The average resistance of the punch 260 - 280 press sintering.

Since a significant increase in the yield of STM crystals has been achieved, a significant economic effect is achieved.

.Formula and sampling

,1. A method of generating ultrahigh pressures in a solid for the synthesis of superhard materials, comprising placing the starting material in a piston-cylinder type superhigh pressure device with a stepped punch and its

axial movement with simultaneous radial compression in an annular chamber filled with plastic material, which requires that, in order to increase the yield of the finished product and improve its quality, after reaching the preset pressure in the annular chamber, the movement of the step punch is carried out at simultaneously removing the plastic material from the annular chamber, thereby providing a predetermined pressure therein.

2. The method according to claim 1, characterized in that the plastic material is removed by expiration through a die with an adjustable cross section.

3. The method according to claim 1, characterized in that the plastic material is passed into containers previously made in the annular chamber, which open after reaching a predetermined pressure and fill up as the punch moves.

Editor

fa 3.2 Compiled by V. Yarovenko Tehred M. Morgenthal Corrector V. Petrash