FR2491775A1 - Mfg. diamonds or boron nitride with diamond structures - by mixing graphite or hexagonal boron nitride with an explosive, and detonating the mixt. in pressure vessel - Google Patents

Abstract

A mixt. is made contg. a convertible material, such as graphite and/or hexagonal BN, plus an explosive; and the mixt. is detonated to obtain powdered diamond or BN with diamond structures. The pref. explosives produce dynamic pressures of 3-60 GPa and temps. of 2000-6000 deg.K.; they are esp. cyclotrimethylene-trinitramine (cyclonite); trinitro-toluene; trinitro-phenylmethyl-nitramine; and/or tetranitromethane. The pref. mixt. contains by wt. 1-70% convertible material and 30-99% explosive. The mixt. may also contain 1-50% addns., esp. water; liq. N2; aq. solns. of metal- or ammonium- salts; hydrazine, or hydrocarbons. Suitable convertible materials include many types or carbon and hexagonal BN. Yields of up to 20% can be obtd. by a simple process.

Description

Process for the preparation of diamond and
diamond-structured varieties of boron nitride.

 The present invention relates to the preparation of very hard materials and more specifically relates to a process for the preparation of diamond and / or varieties with a diamond structure of boron nitride. It is possible to use the aforementioned very hard materials as abrasives as well as as raw materials for obtaining polycrystalline "compacts", that is to say polycrystals from which cutting tools are made. .

The compression of bodies by shock waves gives rise to high dynamic pressures and high temperatures. It allows substances (final products) to be obtained in the form of high pressure phases with high hardness. This is how the impact compression of graphite up to pressures above 20 GPa makes it possible to create the diamond science, vol. 133, NO 3467, published in June 1961 (American Association for the Advancement of
Science, Washington), PS De Carli, JC Jamieson, "Formation of Diamond by Explosive Shock", pp. 1821 1822. The shock wave compression of boron nitride up to pressures higher than 12 GPa makes it possible to obtain a compact variety of this compound fDoklady Akademii Nauk SSSR, volume 172, NO 5, published in February 1967 (Editions " Nauka ", Moscow): GA Adadurov, ZG

Aliev, L.O. Atovmian, T.V. Bavina, Yu.G. Borodko, O.N.

Breussov, A.N. Dremin, A.Kh. Muranevich, S.V. Pershin, Formation of the wurtzite variety of boron nitride in the event of impact compression ", pp.

 1056-10683.

 There are known processes for the preparation of very hard materials, namely diamond and / or varieties with a diamond structure of boron nitride, according to which the materials to be processed are placed, such as graphite and / or hexagonal boron nitride in containers. robust metal, so-called conservation bulbs of the flat or cylindrical type in the walls of which shock waves are generated by detonating charges of an explosive which are in contact with the walls of the bulb or by applying a shock against the walls of the bulbs by means of bodies accelerated to high speeds by the action of the detonation products. The shock waves emitted from the walls of the bulbs penetrate into the convertible material and compress it until it becomes the seat of the required pressures and temperatures. To increase the yield of the final product, other materials are generally added to the material to be transformed. In particular, metals, which in the event of impact compression; heat up to a lesser degree than the high pressure phase which forms (final product). . Ultimately, these additions lower the temperature of the high pressure phase and prevent the annealing of said phase as well as its return to the initial state (US patent 3,401,019, published September 10, 1968, class 23-209.1; GB patent 1 281 002, class CO1B 31/06, published on July 12, 1972).

 There is also known a process for the preparation of said very hard materials according to which the shock waves in the mixture of the convertible material and the additives for cooling are created by the detonation of a charge which is in contact with the surface of the mixture or by impact against such a surface of a body accelerated by the explosion products. The mixture of the starting phase with a cooling additive is in this case in the cavity of a solid and resistant metallic support which protects the body to be treated against splashing (GB patent 1 115 648, published on 29 May 1968, class C0lB 31/06).

 In all known cases of creation of high dynamic pressures and high temperatures, shock compression is used of the convertible materials placed in massive metal containers specially made (ampoules) non-recoverable which are destroyed after opening or which disintegrate in case of explosion, as in the last of the specified cases. All these processes require laborious operations to make and open the bulbs, as well as the consumption of large quantities of construction materials and explosives.

 The object of the present invention is to eliminate the above drawbacks.

 It has therefore been proposed to solve the following problem: in a process for preparing diamond and / or varieties with a diamond structure of boron nitride from a convertible material such as carbon and / or boron nitride, using the energy of an explosion, selecting conditions for conducting the synthesis process which make it possible to obtain said very hard materials without using non-recoverable storage containers, simplifying the technology and the chemical engineering of the synthesis process as well that lower the cost.

 This problem is solved by a process for the preparation of diamond and / or diamond-structured varieties of boron nitride from convertible materials such as carbon and / or boron nitride using the energy of an explosion, it being understood, moreover, that according to the invention, energy from the explosion is used by detonating a charge containing an explosive and the convertible material.

 In the process according to the invention, the detonation of the charge is carried out inside a hollow steel container, sealed before the explosion, having a capacity ensuring a sufficient expansion rate of the gaseous products of the detonation and low residual gas pressures (1 to 5 atm). This makes it possible to use a large number of times (thousands and tens of thousands of times) the container, excluding the use of special, non-recoverable storage bulbs and thereby significantly reducing the consumption of construction materials. The present invention also makes it possible to reduce appreciably (in a ratio of 1/10 to 1/30) the consumption of explosives, since the explosives are in immediate contact with the convertible material, and, therefore, it eliminates the need to create shock waves with a long duration of action as in the known methods.

The method according to the invention also allows
a) to obtain the final products with a better yield (up to 20%),
b) selectively obtain diamond powders homogeneous from the point of view of their particle size composition, including sulinicronic fractions (classes) with grain dimensions not exceeding one micron, without additional fractionation operations,
c) selectively obtain diamond-structured varieties of boron nitride such as the lvûrtzite or essentially the cubic variety.

 It is possible to use the very hard materials obtained. by the process according to the invention both as abrasives and as raw materials for the preparation of compact polycrystals (polycrystallines) from which cutting tools are made.

According to the invention, the materials to be transformed are subjected to the action of high temperatures and high dynamic pressures which arise directly in the detonation wave of condensed explosives and, more precisely in the front of the detonation wave, in the reaction zone and in the detonation products which essentially contain CO, C02, C,
H20, N2.

 The ranges of pressures and temperatures in the process according to the invention are defined by the qualitative and quantitative composition of the charge and they are essentially a function of the nature of the explosive, of its power and of its density.

 It is advantageous to use as explosives substances which supply detonation of the charge with dynamic pressures from 3 to 60 GPa and temperatures from 2000 to 60000K. Such substances include: cyclotrimethylenetrinitroamine (hexogen), cyclotetramethylenetetranitroamine (octogen), trinitrotoluene (trotyl), trinitrophenylmethylnitroamine (tetryl), tetranitroerythrol (TEN), tetranit mixtures (TNT) or tetranit mixtures (TNT) . The maximum pressure depends on the pressure at the chemical peak of the detonation wave which for the hexogen with a density of 1.8 g / cm is 60 GPa while the minimum pressure is defined by the end pressure of the reaction zone which for the trotyl with a density of 0.8 g / cm3 is equal to 3.0 GPa. The abovementioned temperature intervals are determined by the temperatures developed by detonation of a mixture of explosives at high energy with the minimum amount of convertible material and during the detonation of a mixture of low energy explosives with the maximum amount of convertible material (FA Baum, LP

Orlenko, K.P. Stanjukovich, V.P. Chelyshev, B.I.

Shekhter, "The physics of explosion", published in 1975, Editions "Nauka", Moscow, pages 97 to 125, 145 to 152).

 It is essential that very high temperatures (4500 to 6000 K) lead to the melting of the convertible material in the reaction zone, if it is used in the form of a finely dispersed fraction with particle sizes below one micron and at obtaining finely dispersed fractions of final products. It is essential that during the projection of the explosion products containing particles of final product, the speed of their adiabatic cooling is approximately 108 degrees / second, which significantly reduces the thermal annealing of the final products and their graphitization.

 The method according to the invention provides for the use of charges containing from 30 to 99% by mass of explosive and from 1 to 70% by mass of convertible material.

 To prevent the chemical reaction of the convertible material with the heated detonation products as well as to preserve the final product in the detonation products, it is recommended to use a charge containing, together with the explosive and the convertible material additives inert with respect to the convertible material which evaporate or decompose downstream of the front of the detonation wave, at a rate of 1 to 50 wD of the mass of the charge. Inert additives such as water, ice, liquid nitrogen, aqueous solutions of metal salts, hydrous crystals decompose or evaporate with heat absorption, lower the temperature of the detonation products and, thus, contribute to the conservation of the final product in the products of the detonation. Substances such as ammonium salts, hydrazine, hydrazine salts, aqueous solutions of hydrazine salts, liquid hydrocarbons or solids in the event of evaporation or decomposition form gaseous products chemically inert with respect to the convertible matter which not only cool the products of the detonation, but also dilute them, which also contributes to the conservation of the final product.

 In addition, the method according to the invention provides for the use of a charge containing, together with the explosive and the convertible material, additives which are inert towards the convertible material, namely metals or salts. of metals with a density greater than 2.2 g / cm3. In this case, there is not only an improvement in the cooling conditions of the final product, but also an increase in the average pressure in the reaction zone, even when using weak explosives. In addition, if in the case indicated, carbon is used as the material to transform, a diamond with bimodal distribution of the particles can be obtained according to the dimensions (approximately 0.05-0.5 and 1.0-5.0 microns). .

 The process according to the invention provides for the use of the constituents of the filler not only in the form of finely dispersed fractions, but also in the form of granules prepared from at least one constituent of the filler or else from various combinations of constituents. The granules can have different dimensions and various geometric shapes such as cylinder, disc, sphere, cube, etc.

 To obtain diamonds in particles from 0.05 to 5 microns in size, it is recommended to use hexagonal graphite, rhombohedral graphite, colloidal graphite and pyrolytic graphite as carbon.

 To obtain finely dispersed fractions of diamonds with particle sizes of 0.01 to 1.0 micron, it is recommended to use forms of amorphous carbon with respect to X-rays: smoke blacks, vitrified carbon , coke, shungite, charcoal.

 As the initial boron nitride, it is recommended to use its hexagonal modification or its turbostratic form.

 The method according to the invention provides for the use of an envelope of substance which is inert with respect to the convertible material and capable of dissolving in water, in acids, in alkalis. The charge is introduced into the above envelope before the detonation.

The envelope contributes to prolonging the duration of action of the high pressures and temperatures on the convertible material during the detonation of the charge, which causes, for example in the case of the use of boron nitride, the formation of its variety with cubic structure at high temperature. If the envelope is made of materials such as alkali metal salts, alkali metal carbonate, metal oxides, the envelope disintegrates under the effect of the detonation into small pieces which are easily eliminated from the products of the detonation .

 The process according to the invention provides for the detonation of the charge in an air atmosphere. However, it is advantageous to carry out the detonation of the charge in an inert gas medium with respect to the final products, in an atmosphere of products of the gaseous detonation or under a vacuum of 1.33.1 s to 1.33.1 03 Pa. The observation of these conditions leads to an increase in the yield of the final product since its reaction with oxygen in the air is excluded.

The invention is based on the direct use of high dynamic pressures (preferably from 3 to 60
GPa) and high temperatures (preferably 2000 to 6000 K) developed in the event of detonation of the condensed explosives in order to obtain the diamond and / or modifications to the diamond structure of the boron nitride.

The process is carried out by detonating a charge composed of an explosive and a convertible material as well as, if necessary, additives which are inert with respect to the convertible material and the final products. As aforementioned additives, it is possible to use water, ice, liquid nitrogen, aqueous solutions of metal salts such as sodium chloride, calcium chloride: hydrated crystals such as CuC12 .2H20, CaC12.6H20; ammonium salts such as ammonium chloride, ammonium nitrate, ammonium oxalate; hydrazine, hydrazine salts, especially hydrazine nitrate, hydrazine sulfate, aqueous hydrazine salts such as hydrazine nitrate, hydrazine chloride; liquid hydrocarbons, in particular octane, benzene, nitrobenzene; solid hydrocarbons such as paraffin, polyethylene, rubber; metals or metal salts with a density greater than 3 2, 2 g / cm, in particular copper, iron, calcium carbonate, barium chloride, lead nitrate.

 The inert additives listed increase the yield of final products.

 The method according to the invention provides for the possibility of using convertible materials (carbon and boron nitride) in the form of various varieties, of various particle size compositions. The latter case makes it possible to obtain end products also of various particle size compositions. Carrying out the process with the use of various inert additives under various pressures and temperatures of the detonation makes it possible to obtain final products of imposed varieties, diamond - cubic variety or in the form of a mixture of hexagonal varieties (1 to 40%) and cubic (60 to 99 S) ;; boron nitride - variety with wurtzite structure or as a mixture of cubic varieties (1 to 80%) and with wurzite structure (20 to 99%).

The present invention makes it possible to use the constituents of the filler both in the form of finely dispersed fractions and in the form of granules prepared from at least one constituent of the filler or from various combinations of constituents. In this case, the filler can be a mixture of constituents taken in the form of finely dispersed fractions or else, in the presence of granules, the filler can
- either be presented as a mixture of finely dispersed fractions of explosive with granules of convertible material,
- either be composed of granules prepared from a mixture of explosive and convertible material, and finely dispersed fractions of additives inert with respect to the convertible material,
- either be composed of a finely dispersed fraction of explosive and of granules prepared from a mixture of convertible material with inert additives,
- or be in the form of granules prepared from a mixture of explosive, convertible material and inert additives, etc.

 The above granules can have various dimensions and different geometric shapes such as cylinders, discs, spheres, cubes, etc.

 The invention provides an embodiment of the method according to which the charge is previously enclosed in an envelope of inert substance vis-à-vis the convertible material, capable of dissolving in water, acids, alkalis. As such a substance, it is possible to use in particular sodium chloride, calcium carbonate, lead oxide. The presence of an envelope in the above substance contributes to increasing the action time of the high temperatures and pressures on the convertible material during the detonation of the charge.

 It is possible to detonate the charge in an air atmosphere, preferably in an atmosphere of inert gas with respect to the final products (for example nitrogen, hydrogen, argon), in an atmosphere of gaseous products of the detonation or under a vacuum of 1.33.10 2 to 1.33.103 Pa.

 The method according to the invention is illustrated in the following by a concrete example of implementation which is accompanied by a drawing (single figure) on which is schematically represented a steel container with a load sheltered inside, Next this drawing, in the walls of the steel container 1 are managed four orifices 2, 3, 4 and 5 which are provided with shutters 6, 7, 8 and 9. The orifice 3 is tints when the container 1 is filled. an inert qaz by ranport to the final products. The orifice 4 is intended to remove the tightness of the container 1 after the explosion and to purge the differential pressure due to the release of the gaseous products of the detonation. The orifice 5 is intended to discharge the solid products from the detonation after one or more explosions. The load 10 is mounted on a steel rod 11 (this rod can be made of another material, in particular wood, celluloid) fixed in the shutter 5. In this same shutter are immobilized two electrical inputs 12 intended for connection conductors of a capsule-detonator 13 installed in charge 10.

 To carry out the process according to the invention, the explosive is mixed with the convertible material and, if necessary, with inert additives and a charge of density and absolute mass is obtained. The charge obtained is mounted on the steel rod 11 immobilized in the obturator 6. The capsule-detonator 13 is installed in the charge and its conductors are joined to the electrical inputs 12. The charge 10 is placed in a steel container 1 and the shutter 6 is closed in a sealed manner. Said container is used a large number of times (thousands and tens of thousands of times). The shutter 9 is closed in a leaktight manner and, via the orifice 3, liquid nitrogen is introduced, for example, into the container. After total evaporation of the liquid nitrogen and displacement of the air by the nitrogen gas through the openings 3 and 4, the shutters 7 and 8 are sealed. After applying the voltage to the electrical inputs 12, the charge 10 is detonated. The shutter 8 is opened, the pressure equalized in the container 1 with atmospheric pressure and the solid products of the detonation are discharged through the orifice 5. The final product is isolated from the above-mentioned detonation products by known methods. Thus if the process aims to obtain the diamond, the solid products of the detonation are successively treated with fuming nitric and sulfuric acids in order to eliminate the fragments of the detonator capsule and of the non-diamond varieties of carbon respectively. Then, the insoluble residue is treated with hot concentrated alkali solutions to remove impurities such as silicates, rinsed with water and dried.

If the process aims to obtain diamond-structured varieties of boron nitride, the solid products of the detonation are successively treated with fuming nitric and perchloric acids to eliminate the fragments of the capsule-detonator and the free carbon.

The residue is then treated with a mixture of concentrated sulfuric acid and sodium fluoride (ratio
by mass of components 20/3, respectively) at a
temperature of 2000C to remove boron nitride
hexagonal not converted. The insoluble residue is separated,
it is rinsed and dried at a temperature of 100 C.

The method according to the invention makes it possible to obtain it
diamond and the diamond-structured varieties of boron nitride. in the form of powders having the characteristics i
following
Diamond
Particle dimensions, microns
from graphite 0.05 to 5.0
from carbon black 0.01 al, 0
Specific surface, m2 / g 10 to 120
Density, g / cm3 3.15 to 3.40
Bulk density, g / cm3 0.35 to 1.0
Dimensions of dissemination areas
consistent, A 85 to 200
Value of microdistorsions of the second
genus of the crystal lattice, A a / a O at 2.5.10-3
Concentration in paramagnetic centers,
-I
g
from graphite (1.5 to 4.5). 1019
from carbon black (1.0 to 1.3).
Heat resistance under vacuum for
30 minutes, C greater than 800
Weight loss by vacuum heating
up to 8000C, Yo in mass up to 5.0
varieties with diamond structure of
boron nitride
Particle dimensions, microns 0.05 to 5.0
Density, g / cm3 3.15 to 3.30
Composition by phases, X
cubic boron nitride O to 80
boron nitride with wûrtzite structure 20 to 100
Other features and benefits of the
The present invention will be better understood on reading the description of several concrete examples of its implementation. In all cases, the yield of final product is indicated in percent of the mass of the mixture composed of final product and unconverted initial material (15 to 20% by mass of the convertible initial material are oxidized during the detonation of the charge. ).

EXAMPLE 1
A charge is molded from a mixture composed of 80% by mass of finely dispersed hexogen and 20% by mass of hexagonal graphite with particle sizes less than 300 microns. The load is placed in the center of a container filled with nitrogen. The container is sealed, the detonation of the charge is carried out and the solid detonation products which consist of diamond, unconverted carbon, fragments of the detonator capsule, moisture and adsorbed gaseous products are extracted. of the detonation. The solid products of the detonation are successively treated with fuming nitric and perchloric acids in order to remove the impurities and the unconverted carbon. The residue is treated with a solution of sodium and potassium hydroxides brought to the boil to dissolve the impurities which are silicates.

The residue is separated by centrifugation, rinsed with water and dried at a temperature of 130 C.

The product obtained is a diamond powder which is composed of a mixture of 25% by mass of the hexagonal variety (longsdalite) and 75% by mass of the cubic variety. The dimensions of the powder particles are 0.1 to 3.0 microns. The density determined with the pycnometer is 3.25 g / cm. The concentration 19 paramagnetic centers is equal to 2.0.1019 -1 in paramagnetic centers is equal to 2.0.1019 g
The overall yield in the above varieties of diamond is 1.5% by mass.

EXAMPLE 2
A charge is molded from 1.5 kg of a mixture composed of 66 04 by mass of finely dispersed hexogen, of 17% by mass of hexagonal graphite with particle sizes of 40 to 250 microns and of 17 X by mass of water. The operations are carried out as described in Example 1. The average dynamic pressure at the front of the detonation wave during the detonation of the charge is equal to 8 GPa, the average temperature is equal to approximately 30000K.

 The product obtained is a diamond powder which consists of a mixture of cubic and hexagonal varieties (60 and 40 X by mass respectively). The characteristics of the product obtained are analogous to the characteristics of the product according to Example 1. The overall yield of the indicated varieties of diamond is 2.0% by mass.

EXAMPLE 3
We mold. from a mixture composed of 75 X by mass of finely dispersed hexogen and 25 X by mass of vitrified carbon (dimensions of the particles of vitrified carbon 10 to 300 microns) a charge with a density of 1.1 g / cm3. The detonation of the charge and the subsequent operations are carried out as described in Example 1.

 The product obtained is diamond powder of cubic variety with particle sizes from 0.1 to 5.0 microns, with a specific surface of 40 m2 / g, with a density of 3.15 g / cm3. By heating under vacuum to a temperature of 8000C, the diamond loses 5 X in mass of volatile impurities, its crystal lattice remaining unchanged. The diamond yield is 1.7 X by mass.

EXAMPLE 4
One molds from a mixture of 990 g of finely dispersed hexogen and lo g of Ceylon graphite with particle sizes of 50 to 200 microns containing about 15 to 20% of rhombohedral variety, a charge of a density 1.0 g / cm. The detonation of the charge and the subsequent operations are carried out as described in Example 1.

 The product obtained is a diamond powder which is composed of 70% of cubic variety and 30% of hexagonal variety. The characteristics of the diamond are similar to those of the diamond according to Example 1. The total variety yield of the diamond is 5.0%.

EXAMPLE 5
It is molded from a mixture composed of 85.7% by mass of finely dispersed TEN (tetranitroerythrol) and 14.3% by mass of hexagonal boron nitride with particle sizes of less than 10 microns, a charge during the detonation of which it develops in the front of the detonation wave a dynamic pressure of 30 GPa and a temperature of approximately 50000K. The charge is placed in the center of a container in which a vacuum of lo mm Hg is created. The charge is detonated and the solid products of the detonation are extracted from the container. The solid detonation products are a wurtzitoid modification mixture of boron nitride, unconverted hexagonal boron nitride, boron oxide, detonator residues, moisture, gaseous detonation products adsorbed and impurities such as Free carbon. The solid products of the detonation are successively treated with fuming nitric and perchloric acids in order to remove the residues of the detonator and of free carbon respectively, as well as to remove the boron oxide and the gaseous products of the detonation adsorbed. Then, the residue is treated with a mixture of concentrated sulfuric acid and sodium fluoride (mass ratio 20/3 respectively) at a temperature of 20 ° C. to dissolve the unconverted hexagonal boron nitride. The insoluble residue is separated, rinse with water and dry at a temperature of 1000C.

 The product obtained is of the wurzite structure variety of boron nitride with particle sizes of 0.05 to 5.0 microns and a density of 3.15 g / cm3. The product yield is 2.0%.

EXAMPLE 6
Is molded, from a mixture composed of 30% by mass of finely dispersed hexogen and 70% by mass of hexagonal boron nitride with particle sizes less than 10 microns, a charge whose detonation gives rise to in the forehead of the detonation wave a dynamic pressure of 3 GPa and a temperature of approximately 20000K, detonation of the charge is carried out in an argon atmosphere. The subsequent operations for separating the final product from the solid products of the detonation are analogous to those which have been described in Example 5.

The product obtained is a variety with a wurtzite structure of boron nitride with characteristics similar to those of the product obtained in Example 5.
The product yield is 1.5 X.

EXAMPLE 7
We mold, from a mixture composed of 91 X by mass of finely dispersed hexogen and 9% by mass of spherical granules of 0.5 to 1.0 mm in diameter composed of 50 X by mass of boron nitride hexagonal with particle dimensions less than 5 microns and 50 S by mass of ammonium chloride with particle dimensions from 1 to 100 microns, an average density charge of 1.6 g / cm3. The detonation of the charge is carried out in an atmosphere of gaseous detonation products which have formed during the prior detonation of an identical charge. The subsequent operations are analogous to those which have been described in Example 5.

 The pulverulent product obtained is a mixture of cubic variety and with a wurtzite structure of boron nitride (30 and 70% by mass respectively). The powder consists of particles from 0.5 to 3.0 microns and has a density of 3.30 g / cm3. The overall yield in varieties with a diamond structure of boron nitride is 3.3 X.

EXAMPLE 8
We put a mixture of paraffin, of slow powdered copper (density of 8.9 g / cm3) 'of particle sizes less than 40 microns and of hexagonal natural graphite with particle sizes of less than 500 microns with mass proportions of 1/1/1 in the form of spherical granules of approximately 1 mm in diameter. A charge of cylindrical shape is molded from a mixture composed of 85.7% by mass of finely dispersed hexogen and 14.3% by mass of said granules. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

 The product obtained is a mixture of 40% hexagonal variety and 60% cubic diamond variety. The dimensions of the powder particles are from 1 to 5 microns, their specific surface is 10 M2 / g, their density is 3.40 g / cm3. The overall yield in the above varieties of diamond is 3.5% by mass.

EXAMPLE 9
A load is molded from a mixture of 1.0 kg of finely dispersed hexogen and 0.2 kg of cylindrical granules composed for 80% by mass of powdered iron (density 7.8 g / cm3) with dimensions particles less than 40 microns and for 20% by mass of hexagonal graphite with particle dimensions less than 40 microns and having a diameter of 5 mm and a height of 5 mm. The detonation of the charge is carried out in an atmosphere of air. The operations for separating the final product from the solid products of the detonation are similar to those described in Example 1.

 The product obtained is a mixture of 70% of cubic rivet and 30% of hexagonal variety of diamond. The characteristics of the diamond are similar to those of the diamond obtained in Example 8. The overall yield of the aforementioned varieties of the diamond is 5.0%.

EXAMPLE 10
One molds, starting from a mixture composed of 10% by mass of black oil with a specific surface of 15 m2 / g and 90% by mass of cylindrical granules of 3 mm in diameter and 10 mm height composed of 95% by mass of finely dispersed hexogen and 5 X by mass of paraffin, a filler with a density of 1.1 g / cm3. The detonation and the operations relating to the separation of the final product are carried out in a manner analogous to what was described in Example 1.

 The product obtained is diamond powder of cubic variety with a specific surface of 35.2 / soil of particle size from 0.01 to 1.0 microns, with dimensions of the coherent diffusion zones of 150 A, of a value of microdistorsions of the second kind of the crystal lattice of approximately 1.10 3, of a concentration in paramagnetic centers of 1.3.1019 g 1, The diamond yield is 3.5%.

EXAMPLE 11
A charge is molded from a mixture composed of 75% by mass of trinitrotoluene with particle sizes less than 200 microns, 24% by mass of hexagonal boron nitride with particle sizes less than 3 microns and 1 % by mass of hydrazine. The charge is detonated under a vacuum of 10 mm Hg. The separation operations of the final product are carried out in a manner analogous to that which was described in Example-5.

The product obtained is a variety of boron nitride powder with wurzite structure, with particle sizes of 0.1 to 1.0 microns and density of 3.20 g / cm. The product yield is 2.7% ~
EXAMPLE 12
One molds1 from a mixture composed of 75% by mass of finely dispersed hexogen, 12.5% by mass of hexagonal boron nitride with particle sizes less than 10 microns and 12.5% by mass of dichloride. of copper dihydrate with particle size less than 1 mm, a charge with a density of 1.55 g / cm3. The charge is detonated in an air atmosphere The solid products of the detonation, composed of varieties, are treated with wurtzite and hexagonal structures of boron nitride, detonator residues (primer), decomposition products of copper dichloride, moisture, gaseous products adsorbed from the detonation and free carbon constituting an impurity, by the acid perchloric fuming in order to eliminate the impurities constituted by the free carbon, the humidity and the gaseous products of the detonation. The residue is treated with fuming nitric acid to remove the residue from the detonator (primer) and the decomposition products of copper dichloride, rinsed with water, dried and treated with a mixture of concentrated sulfuric acid and sodium fluoride (proportions by mass of 20/3 respectively) at a temperature of 2000C to dissolve the unconverted hexagonal boron nitride. The residue is separated, rinsed with water and dried at the temperature of 1000C.

 The product obtained is of the wurzite structure variety of boron nitride. The characteristics of the product are similar to those of the product obtained in Example 11. The yield of variety with a diamond structure of boron nitride is 3.5%.

EXAMPLE -13
A charge of a density of 1.2 g / cm obtained from a mixture composed of 75 X by mass of finely dispersed hexogen and 15 X by mass of pyrolytic graphite with particle size less than 200 is molded microns and 10% by mass of saturated aqueous solution of hydrazine nitrate. The charge is detonated and the subsequent operations are carried out in a similar manner to that described in example 1.

 The product obtained is a diamond powder analogous by its composition and its properties to the powder described in Example 4. The diamond yield is 4.0%.

EXAMPLE 14
Is molded from a mixture of 70 X by mass of tetryl with particle sizes less than 300 microns, 20% by mass of black with furnace oil with a specific surface of 15 m2 / g and 10 X by mass of octane, a cylindrical charge of 40 mm in diameter having a density of 1.4 g / cm. The charge is detonated under a hydrogen atmosphere. The other subsequent operations) are similar to those described in Example 1.

 The powdery product obtained is diamond of cubic variety. The density of the powder is 3.23 g / cm3, its specific surface area is 40 m2jg, the concentration of paramagnetic centers is approximately 1.2.1019 g, the dimension of the coherent diffusion zones is 160 The diamond yield is 5.0 S.

EXAMPLE 15
Is molded, from a mixture composed of 80 i by mass of octogen with particle size less than 500 microns, 10% by mass of shungite with particle size less than 100 microns and 10% by mass of rubber with isoprene, a flat load of 5 mm thick, 100 mm wide and 200 mm long. The detonation and the subsequent operations are carried out in a manner analogous to that of Example 1.

 The product obtained is diamond powder of cubic variety, with properties similar to those of the diamond obtained in Example 14. The diamond yield is 5.5%.

EXAMPLE 16
Is molded from a mixture of 80% by mass of finely dispersed hexogen, 10 X by mass of black to 1 thermal oil with a specific surface of 75 m2 / g and 10% by mass of solution saturated aqueous sodium chloride, a charge with a density of 1.5 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

 The product obtained is a cubic diamond powder with a specific surface of 77 m2 / g. The heat resistance of the diamond obtained exceeds 8000C. The diamond yield is 3.0%.

EXAMPLE 17
One molds, from a mixture composed of 30 v by mass of finely dispersed hexogen, of 10% by mass of black with thermal oil with a specific surface of 75 m2Jh and of 10% by mass of '' a 40% aqueous solution of calcium chloride, a load with a density of 1.5 g / cm. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1. The product obtained is analogous in its properties to the diamond of Example 16. The diamond yield is 3.0 X
EXAMPLE 18
We mold, from a mixture composed of 60% by mass of finely dispersed hexogen, 10 X by mass of hexagonal boron nitride with particle sizes less than 10 microns and 30% by mass of calcium chloride hexahydrate , a load with a density of 1.8 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 12.

 The properties of the product which is a variety with a wurtzite structure of boron nitride are similar to those of the product obtained in Example 12. The yield of a variety with a wurtzite structure of boron nitride is 4.0 X.

EXAMPLE 19
Is molded, from a mixture composed of 75% by mass of finely dispersed hexogen, 15 X by mass of pyrolytic graphite with particle sizes less than 200 microns and 10 X by mass of hydrazine nitrate, a load with a density of 1.2 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that described in Example 1.

 The product obtained is diamond powder similar in composition and characteristics to the powder described in Example 4. The diamond yield is 5.0%.

EXAMPLE 20
Is molded from a mixture of 75 X by mass of finely dispersed hexogen, 15 X by mass of pyrolytic graphite with particle sizes less than 200 microns and 10 X by mass of hydrazine sulfate, a load with a density of 1.2 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that which was described in Example 1.

 The product obtained is diamond powder analogous, by its composition and by its characteristics, to the product described in Example 4. Diamond yield: 4.5 e4.

EXAMPLE 21
A charge with a density of 1.2 g / cm3 is molded from a mixture composed of 75% by mass of finely dispersed hexogen, of 15% by mass of pyrolytic graphite with particle sizes less than 200 microns and 10% by mass of one.

40% aqueous solution of hydrazine chloride. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that which was described in Example 1.

 The product obtained is diamond powder analogous, by its composition and its characteristics, to the beam described in Example 4. The diamond yield is 3.5 S.

EXAMPLE 22
A charge with a density of 1.6 g / cm3 is molded from a mixture composed of 75% by mass of finely dispersed hexogen, 17% by mass of hexagonal graphite and 18% by mass of iron particle size from 40 to 200 microns. The detonation of the charge and the following operations are carried out in a manner analogous to that which was described in Example 1.

 The product obtained is diamond powder of cubic variety with bimodal distribution of particles in dimensions: 0.05 to 0.6 microns (30% relative) and 1.0 to 5.0 microns (70% relative). The concentration of paramagnetic centers is around 4.5.1019 g1. The diamond yield is 6.5%.

EXAMPLE 23
A cylindrical charge of 40 mm in diameter is molded from a mixture of 80 X by mass of finely dispersed hexogen and 20 X by mass of turbostratic boron nitride with a particle size of less than 10 microns. it is surrounded by an envelope of compressed sodium chloride, with a thickness of 20 mm. The charge is detonated under a vacuum of 10-1 mm of Eg. The following operations are carried out in a manner analogous to that of Example 5.

 The product obtained is powder composed of 80 X of cubic variety and 20 X of variety with a wurtzite structure of boron nitride. The yield of varieties with a diamond structure of boron nitride is 15 X. The properties of the powder are similar to those of the product obtained in Example 7.

EXAMPLE 24
A cylindrical charge of 30 is molded from a mixture composed of 80 X by mass of octogen with particle size less than 300 microns and 20 S by mass of sugar carbon with particle size less than 300 microns mm in diameter, which is surrounded by an envelope of compressed calcium carbonate, 25 mm thick. The detonation of the charge and the following operations are carried out in a manner analogous to that which was described in Example 1.

 The powdery product obtained is a cubic variety of diamond with particle-powder dimensions of 0.1 to 2.0 microns, with a density of 3.3 g / cm3, of a dimension of the zones of coherent diffusion. 130, at mid odor distortions of the second kind of the crystal lattice less than 5.10 4, with a concentration in paramagnetic centers of 1.35.1019 -lg - The diamond yield is 13.1%.

EXAMPLE 25
A cylindrical charge of 30 mm in diameter is molded from a mixture composed of 79% by mass of finely dispersed hexogen and 21% by mass of extra-pure hexagonal graphite with particle sizes less than 100 microns. with a density of 1.58 g / cm3 which is surrounded by an envelope of compressed sodium chloride, with a thickness of 20 mm. The detonation of the charge and the following operations are carried out in a manner analogous to that described in Example 1.

 The product obtained is diamond powder of cubic variety with particle sizes from 0.05 to 5.0 microns, with a specific surface of 32 m2 / g, with a density of 3.40 g / cm3, of a dimension of the coherent diffusion zones of 85, of a value of microdistorsions of the crystal lattice of the second genus of 1.5 × 10 3, of a concentration in paramagnetic centers of 1.5 × 1019 g-1. The diamond yield is 15.1 S.

EXAMPLE- 26-
A cylindrical charge with a density of from a mixture composed of 83% by mass of finely dispersed hexogen and 17% by mass of hexagonal boron nitride with particle sizes of less than 10 microns is molded 1.65 g / cm and 30 mm in diameter O-On surround the load with a shell of compressed lead oxide, 10 mm thick. The charge is detonated in a nitrogen atmosphere. The solid products of the detonation are treated with fuming perchloric acid until the total elimination of the free carbon. Next, the residue is treated with fuming nitric acid, to dissolve the fragments of the detonator capsule (primer ) and lead oxides. The insoluble residue is treated by a mixture of concentrated sulfuric acid and sodium fluoride (mass proportions of 20/3 respectively) at a temperature of 200 "C, to dissolve the hexagonal boron nitride. unconverted The residue is separated, washed with water and dried at a temperature of 1000C.

 The product obtained is a mixture of the cubic and wurtzite varieties of boron nitride.

Said product is analogous from the point of view of composition and properties to the product obtained according to Example 23.

 The total yield in varieties with a boron nitride diamond structure is 16%.

EXAMPLE 27
A charge of a density of 1.5 g / cm3 is molded from a mixture of 150 g of finely dispersed hexogen with particle sizes less than 100 microns and 50 g of colloidal graphite. The detonation and the subsequent operations are carried out in a manner analogous to that of Example I.

The product obtained is diamond powder with a specific surface of 120 m2 / g, with a dimension of the coherent diffusion zones of 130, with a microdistortion value of the second kind of the crystal lattice of less than 5.10-4, 4 of a concentration in paramagnetic centers of 1.35.1019 gas The diamond yield is 10%,
EXAMPLE 28
A cylindrical charge is molded from a mixture composed of 75% by mass of finely dispersed hexogen and 25% by mass of black obtained by thermal electrocracking from gas. 40 mm in diameter.

The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

The product obtained is a diamond powder of cubic variety with a specific surface of 35 m 2 / g, with a dimension of the zones of coherent diffusion of 7.7. î 3 u, with a value of microdistorsions of the second kind of the crystal lattice less than 5.10-4, concentration in paramagnetic centers of 1.13.1019 g-. The diamond yield is 8.5% *
EXAMPLE 29
From a mixture composed of 75% by mass of finely dispersed hexogen and 25 X by mass of petroleum coke with particle size less than 350 microns, heat treated at 1300 ° C., is molded a charge of density of 1.5 g / cm.

The detonation of the charge and the following operations are carried out in a manner analogous to that of Example 1.

 The product obtained is a diamond powder of cubic variety with particle sizes from 0.3 to 3.0 microns, with a density of 3.27 g / cm3, with a dimension of the coherent diffusion zones of 12.10. The make-up is 12.3%.

EXAMPLE 30
A cylindrical filler with a density of 1.6 g / cm is molded from a mixture composed of 83% by mass of finely dispersed hexogen and 17% by mass of spectrally pure hexagonal graphite.

The detonation of the charge is carried out under a vacuum of 1.33.10-Pa. The subsequent operations are carried out in a manner analogous to that described in Example 1.

 The product obtained is diamond powder of cubic variety whose properties are similar to those of the product obtained according to Example 25. The diamond yield is 20 t.

EXAMPLE 31
A charge in the form of a 60 mm disc is molded from a mixture composed of 79 X by mass of finely dispersed hexogen and 21 X by mass of hexagonal boron nitride with particle sizes less than 10 microns. diameter and 30 mm thick. The detonation of the charge is carried out under a nitrogen atmosphere, with simultaneous initiation by two capsule-detonators arranged at the opposite end faces of the disc along its axis. At the collision limit of the detonation waves propagating in opposite directions, a dynamic pressure greater than 60 GPa arises and a temperature of approximately 60000K. The subsequent operations are carried out in a manner analogous to that which was described in Example 5.

The product obtained is a mixture powder of cubic varieties and with a wurzite structure of boron nitride (70 X and 30 X respectively). The dimensions of the powder particles are between 0.05 and 3.0 microns, their density is 3.3 g / cm. The overall yield in varieties with a diamond structure of boron nitride is 15.0%
EXAMPLE 32
750 g of hexogen are dissolved in dimethylformamide and 250 g of black oil of furnace oil with a specific surface of 15 m2 / g are dispersed in the solution obtained. The suspension obtained is poured into a tenfold quantity of water. The deposit formed is filtered off and dried, which is in the form of a mixture of recrystallized hexogen with particle sizes less than 10 microns with black. A cylindrical charge of 40 is molded from the mixture formed. mm in diameter and a density of 1.5 g / cm
The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

The product obtained is diamond powder of cubic variety, with a specific surface of 59 m / g with dimension of the zones of coherent diffusion of 200 A, with a value of microdistorsions of the second kind of the crystal lattice of less than 5.10, a concentration of paramagnetic centers of approximately 1.25.1019 g 1 The diamond yield is 19.3 X
EXAMPLE 33
From a mixture composed of 450 g of finely dispersed hexogen, 75 g of spectrally pure hexagonal graphite with a particle size of less than 200 microns and 75 g of boron nitride with a particle size of less than 10 microns are molded , a tubular load of 100 mm in diameter and 10 mm in wall thickness, having a density of 1.6 g / cm3. The detonation of the charge is carried out under.

a nitrogen atmosphere. The solid products of the detonation are a mixture of diamond and variety with a diamond structure of carbon boron nitride1 and hexagonal boron nitride, boron oxide, boron carbide, detonator shards, -d ' humidity and adsorbed gaseous products, detonation. The solid products of the detonation are successively treated with fuming nitric and perchloric acids to remove the primer flakes, boron oxide, non-diamondoid forms of carbon and gaseous products of the detonation. The insoluble residue is treated with a mixture of concentrated sulfuric acid and sodium fluoride (mass proportions of 20/3, respectively) at a temperature of 200 C, it is separated and subjected to drying.

 The product is a mixture of cubic variety of diamond, cubic variety of boron nitride and variety with wurzite structure of boron nitride for mass proportions of 70/20/10 respectively.

The overall yield of the above-mentioned varieties of the product is 15 S.

EXAMPLE 34
Is molded, from a mixture composed of 75% by mass of finely dispersed hexogen, 20% by mass of spectrally pure hexagonal graphite with particle sizes less than 40 microns and. 5% by mass of ammonium nitrate with particle sizes less than 1 mm, a flat load with a thickness of 30 mm, a width of 60 mm and a length of 200 mm, with a mass volume of 1.7 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1
The product obtained is cubic modification diamond powder, with properties similar to those of the diamond powder obtained according to Example 25.

The diamond yield is 22%.

EXAMPLE 35
A flat charge is molded from a mixture composed of 80 X by mass of finely dispersed hexogen and 20 X by mass of carbon black obtained in a diffusion flame and having a specific surface of 200 m / g 15 mm thick, 30 mm wide and 150 mm long. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

 The product obtained is diamond powder of cubic variety with an average particle size of approximately 150 A and with a dimension of coherent diffusion zones of 140 A. The diamond yield is 10%.

EXAMPLE 36
A charge with a density of 1.2 is molded from a mixture composed of 75% by mass of finely dispersed hexogen and 25% by mass of natural hexagonal graphite with particle sizes less than 400 microns. g / cm3. The charge obtained is impregnated with liquid nitrogen at a rate of 10% of the mass of the charge. The detonation of the charge and the following operations are carried out in a manner analogous to that of ltexemole 1.

 The product obtained is diamond powder composed of 70 X of cubic modification and 30 X of hexagonal variety. The value of the second order microdistorsions of the crystal lattice for the cubic variety in this product is equal to 2.10'3. The specific surface of the powder is equal to 30 m 2 / g. The overall yield of the above varieties of diamond is 5.0%.

EXAMPLE 37
Is molded, from a mixture composed of 60% by mass of tetranitromethane, 20% by mass of black with furnace oil with a specific surface of 15 m2 / and 20 á by mass of nitrobenzene, a cylindrical load of 40 rn: n in diameter. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1. The dynamic pressure and the temperature which arise as a result of the detonation of the charge of composition indicated are equal to 12 GPa and to 5000 K respectively. The product obtained is diamond powder of cubic variety, analogous from the point of view of its properties to the diamond powder obtained according to Example 32. The diamond yield is 15.

EXAMPLE 38
Granules with a diameter of 5 mm composed of 80% by mass of finely dispersed hexogen, 15 X by mass of spectrally pure hexagonal graphite with particle sizes less than 100 microns and 5 X by mass of polyethylene with a dimension of mixed are mixed. particles less than 100 microns1 in mass proportions of 3/1 with hexogenic I at particle sizes less than 0.5 mm and is molded from the mixture obtained a charge of density that average 1.6 g / cm3, The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

The product obtained is diamond powder of cubic variety with properties similar to those of the diamond powder obtained in Example 30. The diamond yield is 21 Xv
EXAMPLE 39
Is molded, from a mixture composed of 15 X by mass of black with furnace oil with a specific surface of 15 m2 / g, 80 X by mass of finely dispersed hexogen and 5 X by mass benzene, a charge with a density of 1.45 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 1.

 The product obtained is diamond powder of cubic variety similar in its properties to the product obtained in Example 14. The diamond yield is 8 w.

EXAMPLE 40
One molds, from a mixture composed of 40 X by mass of finely dispersed hexogen, 10 X by mass of hexagonal boron nitride with particle sizes less than 10 microns and 50% by mass of barium chloride (density 3 g / cm3) with particle sizes less than 500 microns, a cylindrical load of 40 mm in diameter. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that of Example 12.

 The product obtained is a variety with a wurzite structure of boron nitride with properties similar to those of the product obtained in Example 12. The yield of a variety with a wurtzite structure of boron nitride is 5.0 X.

EXAMPLE 41
We mold, from a mixture composed of 30 X by mass of TEN (tetranitroerythrol) finely dispersed and 70% by mass of vitrified carbon in the form of granules which are blades 1 mm thick with a linear dimension. average of about 8 mm, a cylindrical load of 40 mm in diameter and a density of 1.70 g / cm3. The detonation of the charge and the subsequent operations are carried out in a manner analogous to that which was described in Example 1.

 The product obtained is variety diamond powder with a cubic structure. The product yield is 1.0 X.

EXAMPLE 42
Is molded from a mixture of 80% by mass of finely dispersed hexogen, 1 X by mass of turbostratic boron nitride and 19% by mass of calcium carbonate (density of 2.9 g / cm3), a cylindrical load of 40 mm in diameter and 1.3 g / cm3 of density. The detonation of the charge is carried out under a vacuum of 1 mm Hg. The subsequent operations are carried out as described in Example 5.

 The product obtained is boron nitride powder of variety with a wurtzite structure having properties similar to those of the product obtained in Example 5.

The product yield is 3.5 S.

 As goes without saying, and as it already follows from the foregoing, the invention is in no way limited to those of its embodiments and of application which have been more especially envisaged, it embraces it, on the contrary, all variants.

Claims (13)

 1. Process for the preparation of diamond and / or varieties with a diamond structure of boron nitride from a convertible material such as carbon and / or boron nitride using explosive energy, characterized in that l 'explosive energy is used by detonating a charge containing an explosive and convertible material.  2. Method according to claim 1, characterized in that, as explosives, those used which quarantine during the detonation of the charge dynamic pressures from 3 to 60 GPa and temperatures from 2000 to 6000 K.  3. Method according to claim 2, characterized in that, as explosives, cyclotrimethylenetrinitroamine, cyclotetramethy lnetetranitroamine, trinitrotoluene, trinitro phenylmethylnitroamine, tetra nitroerythrol, tetranitromethane or mixtures of said explosives are used.  4. Method according to one of claims 1 to 3, characterized in that one uses a charge containing from 30 to 99% by mass of explosive and from 1 to 70 X in .mass of convertible material.  5. Method according to one of claims 1 to 4, characterized in that one uses a charge containing, together with the explosive and a convertible material, eqalenlent inert additives with respect to the convertible material which evaporate or are decompose downstream of the detonation wave front, at a rate of 1 to 50 t of the mass of the charge  6. Method according to claim 5, characterized in that a filler is used containing as inert additives water, liquid nitrogen, aqueous solutions of metal salts, hydrated crystals, salts of ammonium, hydrazine, hydrazine salts, aqueous solutions of hydrazine salts or liquid or solid hydrocarbons.  7. Method according to one of claims 1 to 4, characterized in that one uses a charge containing, together with the explosive and the convertible material also inert additives with respect to the convertible material chosen from metals and metal salts with a density greater than 2.2 g / cm.  8. Method according to one of Claims i to 7, characterized in that at least one of the constituents of the filler is granulated beforehand or in various combinations of the constituents of the filler in common.  9. Method according to one of claims 1 to 8, characterized in that quton uses as carbon at least one of its varieties chosen from hexagonal graphite, rhombohedral graphite, loïl neck graphite and pyrolytic graphite.  10. Method according to one of claims 1 to 8, characterized in that one uses as carbon at least one of its amorphous varieties with respect to X-rays chosen from black s, vitrified carbon , coke, shungite and charcoal.  11. Method according to one of claims 1 to 10, characterized in that t as boron nitride, at least one of its varieties chosen from its hexagonal modification and its turbostratic variety is used.  12. A method according to claim 1 to 11, characterized in that before the detonation, the charge is enclosed under an envelope of substance inert with respect to the convertible substance soluble in water, acids, the basics.  13. Method according to "one of claims 1 to 12, characterized in that the detonation of the charge is carried out under an atmosphere of an inert gas with respect to the final products, under an atmosphere of gaseous products of the detonation or under a vacuum of 1.33.10-2 to 1.33.10 Pa.