RU2703212C1 - Method of producing detonation nanodiamonds - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical engineering, specifically to production of detonation nanodiamonds. Method of producing detonation nanodiamonds is carried out by blasting two-component explosive compositions in non-oxidative medium containing tetryl and trinitrotoluene, or hexogen, or trinitrophenol, or other explosive. Explosive charge explosion is carried out in water or water-salt shell (solution of urotropin or disodium salt of ethylenediaminetetraacetic acid (Trilon B)) at weight ratio of charge – explosive mixture : shell 1:(10÷14).

EFFECT: technical result consists in obtaining high-quality detonation nanodiamonds with high output.

5 cl, 4 tbl

Description

The invention relates to chemical technology, namely, to the production of detonation nanodiamonds (DND). DNDs are currently widely used in electroplating, polymer chemistry, in the form of oil compositions, in polishing finishing compositions, medicine, biologists, etc.

The DND production technology is widely known for undermining a mixture of TNT and RDX ~ 50/50 [Danilenko V.V. Explosion: physics, engineering, technology / M .: Energoatomizdat, 2010 .-- 784 p. - ISBN 978-5-283-00857-8; Staver A.M., Lyamkin A.I. Obtaining ultrafine diamonds from explosives // In interuniversity collection. “Ultrafine materials. Obtaining and properties ”, Krasnoyarsk, ed .: rotoprint KrPI. - 1990. - S. 3-22; Danilenko V.V. Features of the synthesis of detonation nanodiamonds // Combustion and Explosion Physics. - 2005. - T. 41, No. 5. - S. 104-116; Dolmatov V.Yu. Detonation nanodiamonds, production, properties, application. - St. Petersburg: NPO Professional, 2011-536 p., Ill., Uv. incl. ISBN 978-S-91259-073-3].

Known methods for producing DND using a large number of different explosives (BB), mixtures thereof, and with the addition of various inert (non-explosive) compounds [Staver A.M., Lyamkin AI Obtaining ultrafine diamonds from explosives // In interuniversity collection. “Ultrafine materials. Obtaining and properties ”, Krasnoyarsk, ed .: rotoprint KrPI. - 1990. - S. 3-22].

However, all these developments remained unclaimed due to low efficiency (low DND yield), scarcity and high cost of explosives, and the high risk of working with both individual compounds and their mixtures.

There are huge unclaimed for direct use in ammunition, reserves of tetryl (N-methyl-N, 2,4,6-tetranitroaniline), which are currently not used.

The closest and only analogue (prototype) is the work of EA Petrova [E.A. Petrov, Study of the physicochemical processes of detonation synthesis of nanodiamonds, Collection of reports of the International Scientific, Technical and Methodological Conference December 22-24, 2004, Kazan, p. 881-888.

According to this method, without a shell (without reservation), the charge obtained by pressing a mixture of tetrile and hexogen (50/50) (density ρ = 1.61 g / cm ³ ) was blown up in an explosive storage chamber and a DND yield of 2.47% by weight initial binary (two-component) mixture.

The disadvantages of the prototype are:

1) Low yield of DND (2.47% wt.), Which makes such production economically unprofitable;

2) Explosion of a cloudless charge with a strong impact of gaseous detonation products (GPA) on the walls and shutoff valves of the chamber, which leads to severe corrosion of the chamber walls (and, accordingly, pollution of the diamond charge (AS) obtained immediately after the explosion with an excess of non-combustible impurities) . The amount of such impurities (metal oxides) can reach up to 30% wt. and more. Such an AS is unsuitable for processing into pure DNDs, especially for direct use in electroplating, polymer chemistry, oils and lubricants, and polishing compositions.

3) The difficulty of removing dry AS, deposited on the walls of the explosive chamber, at least 1/3 of AS is carried away with the gaseous products of the explosion.

The objective of the present invention is to obtain high-quality DNDs using a simple technology with a high yield of two-component charges, including tetryl.

The task is achieved by undermining the pressed binary charge of tetrile with a second explosive compound, which may be trotyl, or hexogen (up to 45%), or trinitrophenol (picric acid, PC) in an aqueous or water-salt reservation (shell) at a mass ratio shell: binary charge = (10 ÷ 14): 1.

In a mixture of tetryl-trotyl and tetryl-trinitrophenol, tetryl is used with a content of 50 to 90% by weight.

In a mixture of tetryl-hexogen use tetryl with a content of from 55 to 95% wt.

An aqueous solution of urotropine or Trilon B. is used as a water-salt coating.

The oxygen balance of the binary mixture is selected within the recommended range of KB from -35 ÷ -65% [Dolmatov V.Yu. Assessment of the applicability of explosive charges for the synthesis of detonation nanodiamonds, STM, 2016, No. 5 (233), p. 109-113. / Dolmatov V. Yu., Assessment of applicability of explosive charges for synthesis of detonation nanodiamonds, Journal of Superhard Materials, September 2016, Volume 38, Issue 5, pp 373-376].

However, the process of obtaining DND is influenced, in addition to KB, by many other controlling factors:

1. The composition of the molecules of explosives and the class of compounds;

2. Charge density;

3. Specific charge power;

4. Detonation conditions: the presence or absence of a shell on the charge, the composition of the gas medium in the chamber.

The charges were detonated in an Alpha-2M explosive storage chamber with a volume of 2.14 m ³ . Undermining was carried out in gaseous detonation products of previous explosions, in a non-oxidizing environment. The charge was placed in a plastic bag with 4-5 liters of H ₂ O or an aqueous solution of urotropine or Trilon B (disodium salt of ethylenediaminetetraacetic acid). Gas detonation (without charge reservation) was carried out by suspending the charge in the center of the explosive chamber. Undermining was carried out remotely.

The use of an aqueous shell (for example, VV Danilenko, Explosion: physics, engineering, technology, M .: Energoatomizdat, 2010. - 784 p. - ISBN 978-5-283-00857-8) in the ratio of H ₂ O: BB = 4: 1 is known. The use of the shell in the ratio of H ₂ O: BB = 1: 6 is also known (Pat. RF No. 2348580, IPC СВВ 31/06, publ. 03/10/2009). The effect on detonation synthesis of a larger ratio of water or saline is not known. The use of any binary tetril charge reservation, including water and saline solutions, is not known.

The use of binary charges is possible only after a mandatory study of mixtures with tetryl, their thermal stability, chemical resistance, sensitivity to shock and friction.

Only after obtaining the relevant data can one come to a decision about the option of forming a charge — by melting or pressing, or about the impossibility of using this type of explosive in principle.

Tests for thermal stability (in non-isothermal conditions) were respectively carried out on a Q-derivatograph (upgraded). The type of sample holder is a quartz crucible with an internal notch for a thermocouple (diameter 8 mm, height 12 mm), the type of thermocouple is platinum-platinum rhodium (rhodium content 10%), the test medium is air, without pumping. The heating rate is 5 ° C / min, the temperature range is 20-500 ° C.

Only after obtaining the relevant data can one come to a decision about the option of forming a charge — by melting or pressing, or about the impossibility of using this type of explosive in principle.

where T _HP - the temperature of the onset of decomposition;

T _nir is the temperature of the onset of intense decomposition.

Conclusion: the conclusion about the compatibility of tetrile with trotyl, hexogen or PC can be made only by the results of studies on the measuring and computing complex "Volcano-2000" (chemical resistance).

Tests for chemical resistance.

The chemical resistance of explosive materials is determined by gas evolution in mm. Hg at the Vulkan 2000 measuring and computing complex at a temperature of 110 ° C for 14 hours without taking into account the pressure for the first hour of heating (average value of 3 ^x parallel experiments).

Conclusion: based on the results obtained, it is clear that binary mixtures are compatible and charges can be obtained by pressing.

Determination of the sensitivity of explosive materials to mechanical stress

Sensitivity to shock was determined according to GOST 4545-87 on the K-44-II head, load weight 10 kg, roller device No. 1; sensitivity to friction was determined according to GOST R 50835-98 on the K-44-II head, load weight 1.5 kg, temperature 20 ° C.

Conclusion: the addition of tetrile to the composition of binary mixed explosives does not significantly affect the sensitivity to mechanical stress. Charges can be made by pressing.

The difference in the technologies for obtaining DND and, especially, in the composition of explosives, strongly affects the properties of nanodiamonds. It can be consistently argued that at present there is no single material called "detonation nanodiamonds." There is no single certificate of quality for DNDs; it is also not known which parameters (properties) of various DNDs are decisive for such a still new type of nanomaterial. The main factors determining the yield and quality of the DND are the explosive charge composition, charge armor (shell) and the composition of the gaseous medium in the explosive chamber.

At present, it is not necessary to confirm the initial clarity of the results of detonation of an explosive charge even with knowledge of the main control parameters of the process, including because of the non-ideal detonation process. Moreover, it is still unknown which reactions and in what sequence occur behind the detonation wave front in the zone of chemical reactions (ZHR). This is understandable: there are no methods, apparatus, and instruments for determining the real kinetics of the explosive decomposition process, taking into account the reaction time ~ 0.1 MKS (10 ^-7 s), temperature ~ 4000 K, and pressure ~ 250000 atm.

The composition of chilled detonation products (PD), including solid carbon, cannot be calculated without experimental implementation.

So, for example, the undermining of the most common for obtaining DNDs of shell-free cast binary charges of TG 50/50 in the work [Staver A.M., Lyamkin AI Obtaining ultrafine diamonds from explosives // In interuniversity collection. "Ultrafine materials. Production and properties", Krasnoyarsk, ed .: rotoprint KrPI. - 1990. - S. 3-22.] Gave the yield of DND at 0%, and in [Babushkin A.Yu., Lyamkin A.I. , Staver AM Features of obtaining ultrafine carbon-based material from explosives // In the collection of reports of the V All-Union Conference on Detonation, Krasnoyarsk, August 5-12, 1991. - 1991. - T. 1. - P. 81-83 .] - yield 8% wt.

The water-based charge reservation is used to quickly cool PD to temperatures below which graphitization of already obtained DNDs does not occur (from ~ 4000 K to ~ 1300 K). However, here the effect of the composition of the reservation is also far from unambiguous. So, in the work [V.Yu. Dolmatov, A. Vehanen, V. Myllymaki, A.S. Kozlov, T.T.B. Nguyen Effect of the composition of the charge reservation on the output of nanodiamonds and the content of impurities // Journal of Applied Chemistry, vol. 91, no. 2, 2018, S. 211-216.] Undermining the composition of TG 50/50 in pure water gives a DND yield of 4.9% wt. The introduction of urotropine into water increases the yield of DND to 6.9% wt., But the introduction of Trilon B dramatically reduces the yield of DND to 3.37%. Thus, it is impossible to predict the result in advance.

The non-ideal detonation, for example, for TG 40/60 charges, leads to the fact that, in contrast to calculations, the amount of CO ₂ generated (which should be ~ 100%) is actually ~ 30%, and CO ~ 70%. All this leads to a significant decrease in the yield of AL and DND [Kuzmin IG, Lyamkin AI, Staver AM Experimental study of the composition of gaseous detonation products of condensed explosives in various atmospheres // In interuniversity collection. "Ultrafine materials. Obtaining and properties", Krasnoyarsk, ed .: rotoprint KrPI. - 1990. - S. 23-28.].

Thus, no theoretical constructs can describe the yield of DND depending on the conditions of its synthesis. So, according to the prototype, the yield of DND from a shell-free charge from tetryl (50%) and hexogen (50%) was 2.47% wt., And the repetition of this experiment in exact accordance with the prototype gave a DND output of ~ 1.03% wt. It can be seen that the introduction of tetryl-containing binary compounds, for example, 50% tetryl and 50% TNT (op. 1-6) in water provides a high DND yield only after increasing the BB: H ₂ O ratio from 1:10 or more.

The increase in the mass of water or an aqueous solution in the shell:

1) Increases the time of DND synthesis from “excess” carbon due to the greater mass of the missile shell, that is, the yield of DND increases;

2) Increases the content of DND in AS (51-63% wt.), Due to the greater transition of "excess" carbon to DND.

3) Increases heat dissipation and reduces DND losses due to graphitization.

An analysis of the data in Table 4 shows that tetryl-based binary mixtures (with TNT, RDX, and PC) both in the aqueous medium and in the medium of aqueous solutions of urotropine and Trilon B with an armor: tetrile ratio = (10 ÷ 14): 1 give a high yield DND (from ~ 6 to 7.2% wt.). In contrast to the prototype, where a mixture of tetrile with hexogen gave a small yield of DND (2.47% wt.), Changing the conditions of blasting from a gaseous medium (shell-less blasting) to a condensed (aqueous) medium or water-salt allows more than 2, 5 times to increase the output, due to the use of water provides a quick heat removal from the explosion products, i.e. the graphitization of already formed DND particles decreases.

It is seen that the introduction of a binary composition with tetryl into the water shell dramatically increases the yield of DND. However, the ratio of shell mass to charge plays a significant role. So, in experiments 2-6, we observe a significant increase in the yield of DND with an increase in the BB: H ₂ O ratio from 1: 4 to 1:14. The yield of DND increased by 1.5-1.9 times, which is very significant.

From comparing data op. 5 and 16, op. 8 and 7, op. 13 and 18 it can be seen that an increase in the BB: armor ratio to 1:15 has almost no effect on the output of DND, ASH and DND content in AS.

Those. a further increase in the BB: armor ratio is not advisable — the consumption of the armor increases without a visible effect.

It is very important for the subsequent use of ASh and for chemical cleaning that the content of DND in ASh is very high - from 40 to 60% wt. The high yield of AS and the relatively low content of non-combustible AS impurities associated with it contributes to the low content of these impurities in DNDs, from 0.3 to 1.3 wt%, which allows the use of these DNDs in various application technologies, including microelectronics, biology, and medicine.

The presence of complexones (urotropine and Trilon B), with the ratio of armor: binary composition = (10 ÷ 14): 1 converts part of non-combustible impurities (metal oxides) into readily soluble complex compounds in water, which positively affects the result of chemical cleaning of DND. In addition, the presence of reducing agents in water (these include urotropine and Trilon B) allows for the decomposition of an explosion to create in the chamber not a weakly oxidizing, but a reducing environment, which also leads to an increase in DND yield and a decrease in the surface defects of DND layers. This, in turn, increases the possibilities of using DND in various fields, including medicine and biology. Explosion energy is spent on the breakdown of urotropin and Trilon B, while also allowing the graphitization of the resulting DNDs to be reduced. A new version of the synthesis of DND from binary mixtures containing at least 50% wt. Tetrile, highly profitable, easy to process.

The residual cost of tetrile is very small, this raw material is available in huge quantities, further storage of tetrile is dangerous - tetrile is a fairly highly sensitive substance and its stability decreases with further long-term storage, which can lead, among other things, to an environmental disaster.

In addition, the undermining of tetrile-based binary charges in an aqueous or aqueous salt medium allows one to reduce the impact on the walls of the explosive chamber, reducing the amount of non-combustible impurities in the AS and DND and increasing the life of the chamber. This makes the resulting products highly competitive.

The output of ASh is quite stable ~ 12-14.5% wt. The essence of the method is illustrated by examples of its implementation.

Example 1. The pressing pressure of binary charges with tetrile was used from 1400 to 2000 kg / cm ² . The mass of the charge is 500 g, the shape is a cylinder having a diameter of 60 mm and a height of ~ 110 mm.

For the synthesis of AS and DND, an explosive chamber with a capacity of 2.14 m ³ Alfa-2M (Russia) was used. Charges were suspended in the center of the chamber in a reservation made of water or an aqueous solution of urotropin or Trilon B and undermined. The liquid reservation was poured into an ordinary plastic bag, the charge was immersed there and hung on a hook welded to the top loading hatch of the camera. The ratio of explosives: H ₂ O (or solution) = 1: 10 ÷ 14. The ratio of the mass of explosives to the mass of urotropine or Trilon B ~ 1: 0.5.

After each 5th blasting, a valve was remotely opened at the bottom of the chamber, and the aqueous suspension of ASh under slight pressure in the chamber flowed into the receiving tank (40 liter can). The resulting suspension of AS was filtered from coarse impurities, then from smaller impurities, subjected to magnetic separation and squeezed from excess H ₂ O in an industrial centrifuge. The ASh paste obtained after pressing (H ₂ O content of 75-85% by weight) was sent to the washing stage. The washing of AS from water-soluble impurities (mainly complex salts of urotropine or Trilon B) was carried out in capacitive reactors (250-500 l), the ratio of dry AS to water = 1: 20 ÷ 40. Typically, 4 washes with cold water (~ 20 ° C) and 2 washes with hot water (~ 80 ° C). Further, the AS was dried on stainless baking sheets at (~ 130 ° C, and when a very thick mass formed, the temperature was raised to 160 ° C (without vacuum). If the charge was reserved with pure water, then the AS was usually not washed, but dried immediately.

The dried AS was crushed, triturated and classified on sieves with a cell of ~ 200 μm. Next, the AS was sent for analysis - the amount of oxidizable carbon was determined (by titration with K ₂ Cr ₂ O ₇ in conc. H ₂ SO ₄ ) and the amount of non-combustible residue was determined by burning the AS sample at 600 ° С, and for chemical treatment (57% nitric acid , t = 230 ° C and p = 80-100 atm.).

All experiments are presented in table. 4 (op. 4-9 and 11-15), performed according to the method described above in Example 1.

Industrial applicability.

The development of the use of binary compounds based on tetrile was made for industrial use. The quality of the obtained DND is very high and a significant demand is expected for “tetrile” DNDs for electroplating (Cr-, Ni-, Zn-, Cu-, Ag-, Au-coatings, anodic oxidation from DND); for polymer chemistry, including adhesive systems; for superfinishing polishing, oil compositions; for biology and medicine.

Claims (5)

1. A method for producing detonation nanodiamonds by detonating two-component explosive compositions in a non-oxidizing medium containing tetryl and at least another explosive substance, such as trotyl, or hexogen, or trinitrophenol, and blasting the charge of the explosive composition is carried out in an aqueous or water-salt shell at a mass ratio of charge - explosive mixture: shell 1: (10 ÷ 14). 2. The method according to p. 1, in which tetryl is used with a content of from 50 to 90 wt.% In a mixture of tetryl-trotyl and tetryl-trinitrophenol. 3. The method according to p. 1, in which tetryl is used with a content of from 55 to 95% wt.% In a mixture of tetryl-hexogen. 4. The method according to p. 1, in which an aqueous solution of urotropine is used as a water-salt coating. 5. The method according to p. 1, in which as an aqueous-salt coating using an aqueous solution of Trilon B.