Annikov V.E., Kondricov B.N. Investigation and Development of New Types of Water-Impregnated Commercial Explosives

Annikov V.E., Kondricov B.N., Mendeleev Chemical Technological University, Moscow, Russia.
Adress: http://www.istc.ru/ISTC/sc.nsf/html/pra.htm?open&id=4003

Investigation and Development of New Types of Water-Impregnated Commercial Explosives

Brief Description of Technology

Over the last two decades, great progress has been achieved in the development and investigation of water-filled (water-impregnated) commercial watergel and water-in-oil explosives at the Laboratory of Chemical Kinetics and Thermohydrodynamics of Reactive Systems of Mendeleev University (Moscow). These explosives have unique features such as favorable rheology, a high detonation ability, good or very good water-resistance, and reliability and safety during production, transportation, and application. They are ecologically friendly and cost-effective commercial products.

Water solutions based on ammonium and sodium nitrates; hydroxylamine nitrate; ADN; sodium-, urea-. methylamine-, ethylenediamine-, and hydroxylamine-perchlorates, containing a variety of water-soluble fuels; finely dispersed, water-soluble aluminum polymers; and cross-linking agents have been investigated.
A number of water-impregnated watergel and water-in-oil commercial explosives has been developed, thoroughly studied, technologically elaborated, and experimentally tested in different branches of Russian industry.

Outstanding performance results were achieved during the course of investigations.

For the first time, detonation characteristics of water solutions of perchloric acid salts with a variety of organic and inorganic cations have been investigated. Areas of low and high velocity detonation (LVD and HVD) have been etermined, and possible mechanisms of chemical interactions at LVD and HVD have been proposed. Catalysis of LVD reactions was discovered, and several effective water-soluble catalytic additives were found.

Low-velocity detonation regimes were observed in diluted water solutions of AN-based mixtures containing water-soluble fuels, and dependencies of the detonation ability on the chemical nature of fuel were distinguished.
Peculiarities in the chemical kinetics of reactions responsible for energy evolution in detonation waves were stipulated using D(d) dependencies experimentally determined for water-impregnated explosive materials, and mechanisms of the leading chemical reactions were proposed.

Steady-state burning of AN-based water-impregnated compositions was observed, the burning rate versus pressure dependencies was derived, and the mechanisms of burning reactions were determined.

Burning and detonation of ADN-based water solutions were studied for the first time. An HVD regime for one of the solutions containing both AN and EADN was found.

A high-voltage electric discharge (the so-called electrohydrodynamic EHD effect) was used for the first time to produce explosions of water-impregnated exothermic formulations, some of which allow one to achieve very good results in gas generation, rock blasting, and destruction of underwater objects.

A water-soluble synthetic polymer, polyacrylamide, was used to produce water-impregnated explosive materials. Rheology characteristics of the materials were studied, cross-linking agents were selected, and the process of compositional thickening was examined. The formulations thickened by polyacrylamide demonstrated very good rheology characteristics and outstanding physical stability: a lifetime up to at least ten years for charges of PAA-based watergel compositions sensitized by pigment grade aluminum were attained.

Military high explosives, propellants, and gunpowders extracted from different kinds of ammunition are used for power and brisance of water-filled composition augmentation for preserving the positive characteristics of water-impregnated systems. A set of compositions containing gunpowders, explosives, and propellants (or their components, in particular, RDX, RDX/TNT, PETN, and Pentolite) are elaborated on the water-impregnated matrix base, including water solutions of ammonium, sodium, and calcium nitrates, as well as hydroxylammonium and sodium perchlorates and hydroxylammonium nitrate.
Theoretical models of detonation and burning of water-filled compositions of different types have been created, including a theory of detonation and combustion wave stability and initiation and extinguishment mechanisms. Deviations of watergel and water-in-oil explosive detonations from the thermodynamic ideal have been elucidated.

A theory of gas-bubble generation and coalescence has been developed based on Lifshitz-Sleozov’s theory of crystallization, on one hand, and De Fries’ approach to the influence of foam bubbles on the dimension distribution, on the other hand.

A theory of hot spot initiation by fast compression of gas intrusions and the viscoplastic flow of the compressed media has been developed. The mechanisms of explosion initiation at shock waves, fragments, or bullet impacts, as well as at low-velocity impacts, blow, or friction have been clarified. The theory of sensitization of the compositions under study has been elaborated. The fundamentals of the theory of the safety of the explosives of this class compared with EM of other classes have been created. Deflagration to detonation transition peculiarities, possibilities of dangerous low-velocity detonation, and high-velocity burning regimes have been manifested.
The kinetics of water-in-oil emulsion formation has been investigated. Differential equations of generation and destruction of water-in-oil globules has been created, analytically solved, and compared with the experimental data.
As a result of physicochemical, hydrodynamic, and rheological exploration of the systems under consideration, a set of energetic materials of the overall class of water-impregnated systems was developed, technologically checked, and practically employed. The most representative types of the compositions elaborated are:

— Watergel systems containing pigment grade aluminum and water-soluble fuel to produce flexible, elongated small-diameter charges for geophysical exploration of oil and gas fields by the method of continuous linear sources of seismic waves.

— Compositions and charges for geophysical investigations by the method of a set of discrete sources of seismic waves in the zone of low sound speed of superficial layers of the Earth.

— Low-density compositions and charges for metal welding and precise blasting works.

— Exothermic formulations for electrohydrodynamic, EHD, applications.

— Compositions of low vulnerability for use in regimes of burning and detonation.
—Permissible explosives for coal mines.

— Commercial water-impregnated formulations containing conversional high explosives, gun powders, and propellants.

— Compositions for commercial booster production.

Legal Aspects

Patent applications for the watergel explosives accepted by industry and their methods of manufacturing and practical application (see section 4) have been approved in Russia. An experimental series of explosives has been tested at State Mining Institutes and recommended for industrial production and use by the Federal State Mining and Technology Supervision Office (Gosgortekhnadzor RF).

Special Facilities in Use and Their Specifications

The experimental facilities of the Laboratory of Chemical Kinetics and Thermohydrodynamics of Reactive Systems of Mendeleev University (Moscow) are located in the region of Tushino, near the edge of the city. It is equipped with explosive chambers having a volume up to 40 m3, modern high-speed process registration devices (streak cameras ZHFR, SFR, VFU, oscilloscopes, and electronic timers), technological apparatuses for production of the compositions in quantities necessary for investigation, UV- and IR-spectrophotometers, gas- and liquid/gas chromatographs for analytical purposes, etc.