RU2119903C1 - Pyrotechnic composition detonating under action of shock-wave loadings - Google Patents

Abstract

FIELD: blasting operations. SUBSTANCE: invention relates to pyrotechnic compositions to provide detonation with no use of explosives and using laser-emission sources. Composition of invention detonates under action of shock-wave loadings as well as from laser impulse with low energetic operation threshold showing low sensitivity to mechanical action and low critical detonation diameter to be employed in laser initiation systems and distinguished by elevated noise-immunity and safety. Main point of invention consists in that composition containing ammonium perchlorate (oxidant) and hypophosphites (fuel), namely: sodium, potassium, and ammonium hypophosphites, individually or as mixtures. Composition further contains fluoro-rubber, fluoroplastic, colloxylin, and phenol- formaldehyde resin. Composition is applicable in mining, oil- production, and other areas. EFFECT: increased safety. 2 tbl, 2 ex

Description

 The invention relates to pyrotechnic compositions detonating under the influence of shock wave loads, in particular a laser pulse, intended for explosive means without using explosives (BB) using laser radiation sources (laser pulse) and can be used in mining, oil production and other fields National economy.

 An increase in the requirements for the stability of detonation systems under conditions of strong electromagnetic fields (lightning discharges, stray currents) [1] and ensuring safety necessitate the development of fundamentally new ways of initiating explosives with an increased degree of noise immunity and safety of the system as a whole. Laser initiation of charges in this sense is the most promising, as it allows you to abandon the very long electrical circuits, the most vulnerable in traditional schemes of detonation. Laser means of initiation (LSI) are based on the effect of monochromatic radiation on an explosive either directly or through optical fibers, which sharply increases the resistance of these systems to induced electromagnetic pulses and static electricity. The use of lasers with different radiation wavelengths, different intensities and pulse durations, as well as radiation modes (free generation, modulated Q-factors) as radiation sources makes it possible to widely control the sensitivity of the system as a whole.

It is known that the most sensitive to laser radiation are standard initiating explosives (TRS), the critical density of initiation energy (H _cr ) of which is ~ 5-10 mJ / cm ² . However, the very high sensitivity of TRS to external influences and, first of all, to mechanical (friction and impact) significantly reduces safety and limits their use in laser means of initiation. A significant disadvantage of TRS is also that their sensitivity to laser radiation depends to a large extent on the compaction pressure (relative density), especially in the case of “short” laser pulses (τ _and <300 ns).
Blasting explosives (BWS) are safer, but at the same time they are significantly inferior to the IWS in sensitivity to laser radiation (H _cr = 15-20 J / cm ² ).

 Of considerable interest in this aspect are pyrotechnic compositions (PS). The expediency and prospects of their use is due to the fact that they, having a significantly lower sensitivity to mechanical stresses, are more sensitive than IWV to laser radiation in the Q-switched mode and especially in the free-running mode, compared to the explosive explosive.

 Known pyrotechnic compositions under the action of laser radiation either ignite and burn, or are not initiated at all (highly metallized) [2] and therefore are not used in laser detonation circuits based on detonation modes.

 Among the industrial explosives using ammonium perchlorate (PHA), the most famous are triamite 129 anti-grit, dynamos (US Pat. 17393, Poland), ionkites, sheddites, territes (US Pat. 30408, Sweden, 1909; US Pat. 26334, England, 1910; US Pat. 1058891, USA, 1913; US Pat. 1061774, 1913; US Pat. 422727, France, 1910; US Pat. 317030, Germany, 1917), Almatites, blastins (England), Cainites (France), perramons, various perchloratites [3, 4]. Perchlorate explosives were widely used in Japan (karlites), in France and Sweden (sevronites) [5, 6]. In the formulations of the above explosives, in addition to ammonium perchlorate, as one of the oxidizing agents, either ammonium nitrate or alkali and alkaline earth metal nitrates are present, and combustible paraffin, castor oil, wood flour, trinitrotoluene and other nitro derivatives, or mixtures thereof. French sevronites together with ammonium perchlorate include TEN, and in Sweden ammonium perchlorate is a part of nitroglycerin explosives.

 As an example, in table. 1 shows some of the above formulations of perchlorate explosives.

 The prototype of the invention for the most common signs and purpose selected composition, including 86-92% wt. ammonium perchlorate and 8-14% wt. paraffin wax [4].

 The disadvantages of the composition of the prototype are: a large critical diameter of detonation (> 15 mm) when initiated by conventional means of detonation (CD, TRS), the need for an additional detonator, low detonation speed (3200-3700 m / s), very high sensitivity to mechanical stress, and especially shock (95-100%), as well as the impossibility of initiating a detonation transformation under the influence of a laser pulse. Perchlorates as oxidizing agents give a large energy gain in comparison with ammonium nitrate [6]. However, ammonium perchlorate has a fairly high sensitivity to shock - 70-80% in a standard sample. The presence of water in PCA significantly reduces its sensitivity and explosiveness. Humidified to 10% ammonium perchlorate loses its ability to explode. Only in dry form should PCA be classified as explosives [5]. Ammonium perchlorate, like ammonium nitrate, does not explode in the absence of a strong shell from CD; in open charges, it detonates from an intermediate detonator with a charge diameter of at least 60 mm [4, 5].

According to Cast, the PCA detonation velocity is 2500 m / s (in an iron pipe with a diameter of 3.5 cm, with a density of 1.17 g / cm ³ and with the initiation of 110 g of picric acid). According to the data of Naum and Aufschlager, the velocity of PCA detonation in an iron pipe with a diameter of 60 mm is 3800 m / s [5]. It was noted in [7] that the velocity of PCA detonation at a relative density of 0.5 ^° C0.8 is in the range of 3000–4500 m / s with very significant charge diameters from 35 to 76 mm.

 Thus, summarizing the above, we can draw the following conclusions. Ammonium perchlorate, the only one of the components of the proposed compositions, is capable of detonation transformation under the influence of powerful initiators, however, this is possible only with large diameters and in the presence of a strong shell, and its detonation speed is relatively low.

 Therefore, the development of pyrotechnic compositions (PS), detonating under the influence of laser radiation and transmitting the detonation process at small critical diameters and less, in comparison with the prototype, sensitivity to mechanical stress is a very urgent task and is the essence of this invention.

 The problem to which the invention is directed is to develop a composition of detonating from shock-wave loads, as well as from a laser pulse with a low energy threshold, having low sensitivity to mechanical stress and a small critical diameter of detonation for use in laser initiation systems, characterized by increased noise immunity and safety.

The essence of the invention lies in the fact that the composition comprising the oxidizing agent ammonium perchlorate and fuel, as fuel contains salts of hypophosphorous acid (hypophosphites) in the following ratio, wt. %:
Ammonium Perchlorate - 30 ^o C 92
Hypophosphorous acid salt (hypophosphite) - 8 ^o C 70
As salts of hypophosphorous acid, the composition contains an alkali metal salt (sodium, potassium) or an ammonium salt in the form of individual components or mixtures thereof. These compounds are not methods for detonation transformations even under the influence of very powerful initial pulses.

According to the invention, the pyrotechnic composition includes a binder selected from the group: fluororubber (SKF-32), fluoroplastic (F-42L, F-42V), colloxylin, phenol-formaldehyde resins (SF-340, SF-342, SF-0112A) in an amount of 0 , 2 ^o C4% wt. The technical result is achieved by using as combustible components of the pyrotechnic compositions of salts of hypophosphorous acid (hypophosphites) in combination with ammonium perchlorate. This principle of the composition of the PS formulation allowed for the first time to develop compositions with increased sensitivity to shock-wave loads and, in particular, to laser radiation. The compositions stably detonate under the influence of laser radiation (λ = 1.06 μm) of nanosecond duration in the mode of Q-switched and millisecond duration in the mode of free generation at a speed of 4500-6000 m / s at small critical detonation diameters (up to 2 mm without shell). The detonation mode of transformation of the developed compounds under the influence of laser pulses is due to the fact that hypophosphites disproportionate with the formation of chemically highly active products - phosphines, diphosphines, hydrogen, which contribute to the development of chain processes and ultimately lead to the development of detonation transformation.

 The lower limit of the content of salts of hypophosphorous acid is 8% wt. and the upper limit is 70% wt. determined by the decrease in the susceptibility of the PS to the laser pulse (a sharp increase in the threshold). Introduction to PS as a binder of fluororubber, fluoroplastic, colloxylin or phenol-formaldehyde resin can improve the technological properties of the compositions (flowability, uniformity, the possibility of volumetric dosing), as well as physico-chemical resistance and increase hydrophobicity. The lower limit of the introduction of the binder is 0.2% wt., Determined by technological considerations. The upper limit is 4% wt. , is determined by the decrease in the sensitivity of PS to laser radiation.

Thus, the introduction of ammonium perchlorate as a combustible component of salts of hypophosphorous acid into the composition containing the oxidizing agent made it possible to obtain PS stably detonating under the action of laser radiation with a small critical diameter of detonation and low sensitivity to mechanical stresses. The specified set of properties allows the use of the pyrotechnic compositions proposed by this invention in laser initiation systems, characterized by increased safety and noise immunity. Compositions, unlike TRS, can be transported both in finished form and in equipment, and their manufacture is safer. In addition, the composition of the explosion products (H ₃ PO ₄ , HCl, N ₂ , H ₂ O, P ₂ O ₅ , etc.), some of which (H ₃ PO ₄ ) are highly effective flame arresters, as well as the maximum explosion temperature, are not exceeding 1900 ^o C, allows the use of these mixtures as safety explosives intended for use in mines hazardous by dust, and with appropriate adjustment of the formulation in the proposed range of fuel content (in order to reduce the temperature of the explosion) and in mines hazardous by gas.

The combination of ammonium perchlorate with salts of hypophosphorous acid (hypophosphites) can significantly reduce the threshold characteristics of laser initiation of mixtures while reducing the sensitivity of the developed compositions to mechanical stresses. The residual moisture content of the components used for the preparation of the compositions should not be less than 0.3-0.5%. The critical diameter of the detonation of the mixtures is ≈ 2 mm (without shell), and the detonation velocity reaches 6000 m / s, i.e. at the level of TNT at a similar density. The mixtures stably detonate both from traditional detonation pulse sources (ED-8) and from a laser pulse (λ = 1.06 μm) at an energy density of ≈ 1-10 J / cm ² . When tested on the Weler tool (standard method for determining the sensitivity to shock of explosive substances), PCA mixtures with hypophosphites do not work, and when determining the sensitivity to shock according to GOST 4545-80, 70-90% of responses were obtained (Table 2).

 Thus, the compositions proposed in this application have a significantly lower sensitivity to mechanical stress compared with the explosive impact and a higher sensitivity to laser radiation than the explosive explosive, differing in this small critical diameter of the detonation.

 The invention is illustrated by the following examples of the manufacture of mixtures.

Example 1
Obtaining a composition containing (% wt.):
Ammonium Perchlorate (NH ₄ ClO ₄ ) - 30
Sodium phosphate, 1-aqueous (sodium hypophosphite - NaH ₂ PO ₂ • H ₂ O) - 70
Pre-prepared, according to the technology generally accepted in pyrotechnic production, components (drying, grinding, sieving) are metered in a weighted manner and loaded into a mixer. Produce a bag for 10-15 minutes. The finished composition is molded by a method of blind pressing into products.

Example 2
Ammonium Perchlorate (NH ₄ ClO ₄ ) - 66
Ammonium phosphoric acid (ammonium phosphinate, ammonium hypophosphite - NH ₄ H ₂ PO ₂ ) - 32
Fluororubber SKF - 32 - 2.0
All preliminary operations for the manufacture of a dry composition are carried out analogously to example 1. Then, a binder (SKF - 32) is introduced into the composition in the form of a 5% solution in acetone and a wet bag of the composition is produced for 5-10 minutes. After this, the operation is carried out by drying (removal of excess solvent) and granulation (wiping through a mesh with a mesh size of 1.25 mm). Granulation nets can be silk or brass. After granulation, a preliminary and final drying of the composition is carried out at a temperature of 50 ± 5 ^o C. Further, similarly to example 1.

 The critical parameters of the initiation of compositions by laser radiation were determined using a glass laser with neodymium operating in the Q-switched mode. The pulse duration at the half power level was ≈ 30 ns, the radiation wavelength was 1.06 μm, and the maximum pulse energy was 60 mJ. The laser radiation was focused by a lens on the surface of the sample. The energy supplied to the sample was varied by neutral light filters and was estimated using a nanosecond FN-M photometer. Samples for testing were prepared by the method of blind pressing into a shell with a diameter of 6 mm. The thickness of the pressed samples ranged from 2.5 to 5 mm, depending on the formulation of the composition, relative density ≈ 0.8.

 The speed and critical diameter of the detonation of the mixtures, as well as the sensitivity to mechanical stress and the initiating pulse, were determined by standard methods [6]. The calculation of the thermodynamic parameters and the equilibrium composition of the reaction products was carried out using the ASTRA software package [8].

 The obtained test results are given in table. 2.

Literature
1. Epov B.A. Explosive basics. M .: Military Publishing, 1974.- 222s.

 2. Dudyrev A. S., Golowchak A.N., Chumak F.A. Preignition Processes in Laser Ignition of Pyrotechnics // Proceedings of Zel'dovich Memorial International Conference on Combustion. Combustion Detonation, Shock Waves. Russian Section, Moskow, 1994, v. 2, -pp. 117-119.

 3. Bostanzhoglo K. F., Rossi B. D. Ammonium nitrate explosives. M .: Oborongiz, 1940 .-- 135 p.

4. Blinov I. F. Chlorate and perchlorate explosives. M .: Oborongiz, 1941 .-- 102 p. (prototype - p. 84-85)
5. Svetlov B.Ya., Yaremenko N.E. Theory and properties of industrial explosives, M .: Nedra, 1966. - 232s.

 6. Dubnov L.V., Bakharevich N.S., Romanov A.I. Industrial explosives. M .: Nedra, 1988 .-- 358 p.

 7. Johansson K., Person P. Explosive detonation. M .: Mir, 1973.- 352s.

 8. Trusov B.G. Simulation of chemical and phase equilibria at high temperatures. User guide. M .: MVTU im. N.E.Bauman, 1991 .-- 17 p.

Claims (1)

1. Pyrotechnic composition, detonating under the influence of shock-wave loads, including ammonium perchlorate and fuel, characterized in that as fuel it contains salts of hypophosphorous acid in the following ratio of components, wt.%:
Ammonium Perchlorate - 30 - 92
Hypophosphorous acid salts (hypophosphites) - 8 - 70
2. The pyrotechnic composition according to claim 1, characterized in that, as salts of hypophosphorous acid, it contains alkali metal salts: sodium, potassium or ammonium salt, or mixtures thereof
3. The pyrotechnic composition according to claim 1 or 2, characterized in that it further comprises a binder selected from the group: fluororubber, fluoroplast, colloxylin, phenol-formaldehyde resins in an amount of 0.2 - 4.0 wt.%.

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