Investigation of Diamond Synthesis from a Mixture of an Explosive with a Carbon Additive Using a Tracer Technique

The synthesis of detonation diamonds from a mixture of RDX labeled by C¹⁴ isotope with soot was studied experimentally. It was shown that a considerable portion of the diamonds (24.7 ± 3.4)% are formed from the carbon of RDX molecules. The degree of conversion of the carbon atoms of soot to the diamond phase is (16.0 ± 1.6)%. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 117–118, September–October, 2005.     

Specific Features of Synthesis of Detonation Nanodiamonds

It is demonstrated that the Chapman-Jouguet parameters for high explosives used in nanodiamond synthesis are located in the region of liquid nanocarbon; therefore, the chemical reaction zone of the detonation wave involves formation of carbon nanodroplets, which are later crystallized into nanodiamonds on the segment of the isentrope of expansion of detonation products, passing through the region of stability of nanodiamonds in the pressure range of 16.5–10 GPa and the temperature range of 3400–2900 K. Soot in the resultant mixture is the product of amorphization of nanodroplets rather than graphitization of ultrafine diamonds. The influence of detonation conditions of high-explosive charges in an explosive chamber on nanodiamond synthesis is analyzed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 104–116, September–October, 2005.     

Shock densification of ultradispersed diamond

The production of densified ultradispersed diamonds is examined. Methods for preliminary removal of impurities from samples and shock densification are proposed which make it possible to obtain compact materials with durability comparable to that of AS2 synthetic diamond. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 3, pp. 143–145, May–June 1999.     

Isotope studies of detonation mechanisms of TNT,RDX, and HMX

An analysis is performed of experimental data from isotopic tracer studies of the detonation mechanism and formation of the diamond phase of carbon in the detonation products of TNT, RDX, HMX, and their mixtures. Dependences of the relative yield and phase composition of carbon in the detonation products of components of composite explosives on the particle sizes of the explosives are given. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 96–103, September–October, 2007.     

Extraterrestrial,terrestrial and laboratory diamonds — Differences and similarities

Characterization tools such as confocal Raman micro-spectroscopy, Laser Ablation (LA-ICP-TOF-MS) and SEM-EDS were used to characterize meteorites: primitive achondrite — not classified NWA XXX ureilite found in 2006 in Morocco and the graphite nodula from the Canyon Diablo iron meteorite. The presence of diamond was confirmed in both samples.There are two kinds of meteoritic diamonds: diamonds of the sizes of microns up to millimeters are most probably of impact origin, nanodiamonds of the sizes of 1–3 nm, called presolar diamonds because of the isotopic anomalies, are believed to be formed before our Solar System was formed. There are many theories concerning presolar diamonds formation, among them: impact shock metamorphism driven by supernovae or chemical vapor deposition (CVD) from stellar outflows.We examined the properties of diamond nanopowders obtained by the PA CVD and detonation methods. Nanodiamonds obtained by the detonation method, called ultradispersed detonation diamonds (UDD), are of the same range of sizes as presolar diamonds.The results show both differences and similarities among meteoritic, terrestrial and laboratory diamonds. The comparison will help to understand the processes during presolar nanodiamonds formation.     

Optical characterization of nanocarbon phases in detonation soot and shocked graphite

Raman spectroscopy, photoluminescence and FTIR absorption were used to characterize the carbon phases in detonation soot and shocked graphite samples. Detonation synthesized diamond and shock synthesized diamond, which were separated from the detonation soot and shocked graphite respectively, were also collected for further examination. The detonation soot was obtained under different charge conditions and environmental conditions including gas and water, and the diamond was separated from the detonation soot by different purification methods. Size-induced transformation in the Raman and photoluminescence spectra was observed. Sp² carbon is a dominant defect in both detonation synthesized diamond and shock synthesized diamond. The two dynamically synthesized diamonds have similar structure and surface properties. The properties of detonation soot and detonation synthesized diamond are influenced by charge conditions and environmental conditions. The diamond and graphite crystallites in detonation soot and shocked graphite are both in nanometer sizes. The diamond and graphite crystallites in detonation soot have a smaller size and are more disordered than those in shocked graphite.     

Electron paramagnetic resonance spectra in fullerite and detonation diamond

An examination of electron paramagnetic resonance spectra in samples of ultra disperse detonation diamond showed that they contain fullerite as impurity. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 4, pp. 100–101, July–August 1999.     

Phase Diagram of Nanocarbon

In the phase diagram of carbon, the positions of the melting and thermodynamic-equilibrium curves of detonation nanodiamonds or ultrafine diamonds are found as functions of diamond particle size. The position of the set of triple points located in the ranges of pressure 13.5–16.5 GPa and temperature 2210–4470 K and determining the region of the liquid state of nanocarbon is determined. In the phase diagram of nanocarbon, the diamond region is divided into three parts according to the type of nanoparticles: nanodiamond, liquid nanocarbon (nanodrops), and amorphous nanocarbon.__________Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 4, pp. 110–116, July–August, 2005.     

Synthesis of ultrafine diamonds from alloys of TNT with polycyclic nitramines

The synthesis of ultrafine diamonds from alloys of TNT with new polycyclic nitramines was studied experimentally. The use of nitramines with an oxygen balance smaller than that of RDX increases the yield of ultrafine diamonds. An increase in the particle size of the sensitizer in the TNT alloys was shown to result in a higher yield of diamonds. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 131–134, July–August, 2006.     

Detonation combustion of gas mixtures using a hypervelocity projectile

This paper considers, from a unified point of view, problems of initiation of detonation combustion of a gaseous mixture using a hypervelocity projectile (HVP), The consideration is based on the energy criterion forHVP-induced detonation initiation. Experimental results are given that support the correctness of the criterion in a wide range of diameters (5–250 mm),HVP velocities (800–3500m/sec), and compositions of explosive mixtures (from active fuel-oxygen to hard-to-detonate fuel-air mixtures). The processes ofHVP interaction with an explosive mixture are classified. The previously unknown effect of jet formation of a detonation wave from a ballistic wave (at velocities less than the detonation velocities) was discovered for anHVP with a plane bow. Lavrentśev Institute of Hydrodynamics, Siberian Division, of the Russian Academy of Sciences, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 5, pp. 85–102, September–October, 1997.     

Detonation of nitrobenzene and propargyl alcohol

Detonation of mononitrobenzene and propargyl alcohol at reduced pressure is recorded for the first time in 10-mm-diameter steel tubes with a wall thickness of 13 mm with high-power initiation. The detonation velocities of nitrobenzene equal 25–50% of the ideal value obtained from thermodynamic calculations. The conditions for stationary detonation propagation are examined and the critical porosities for these materials are computed based on calculations of the fraction of material that is heated and burnt up during detonation. The computations are in good agreement with experiment. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 1, pp. 89–97, January–February 1999.     

Solid-state detonation velocity limits

The ranges of solid-state detonation velocities are estimated, based on the volume velocity of sound in the reacting mixture (lower limit) and the wave velocity corresponding to the pressure of polymorphic transformation of the product with formation of a more dense phase (upper limit). The latter values are consistent with gas-dynamic estimates of detonation velocities and correlate with detonation velocities of typical high explosives. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 104–106, September–October, 2007.     

Detonation Velocity of Emulsion Explosives Containing Cenospheres

The detonation velocity of an emulsion explosive containing hollow alumosilicate microspheres (cenospheres) as the sensitizer is measured. The size of the microspheres is 50–250 μm. The relations between the detonation velocity and the charge density and diameter are compared for emulsion explosives containing cenospheres or glass microballoons as the sensitizer. It is shown that for a 55 mm diameter charge, the maximum detonation velocity of the composition with cenospheres of size 70–100 μm is 5.5–5.6 km/sec, as well as for 3M glass microballoons. The critical diameter for the emulsion explosive with cenosphere is 1.5–2 times larger than that for the emulsion explosive with glass microballoons and is 35–40 mm. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 119–127, September–October, 2005.     

Low-velocity detonation limits of gaseous mixtures

Low-velocity detonation regimes in acetylene-oxygen mixtures are studied experimentally. Data are obtained on the kinematics of detonation waves and on the boundaries of the high-velocity, galloping, and low-velocity detonation regions. In lean mixtures, the lower pressure limit for the detonation regimes in narrow channels is found to be an order of magnitude lower than assumed previously under the assumption that the limiting detonation is always spin detonation. The major structural characteristics of low-velocity detonations are calculated. The boundary between low-velocity and galloping detonation is found to correspond almost exactly to equality between the induction time in a particle and the time for it to move from shock wave to flame. Nearly harmonic oscillations of the flame are observed with periods that are related to the longitudinal size of low-velocity detonation waves. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 3, pp. 89–96, May–June 1999.     

Detonation of propane-air mixtures under injection of hot detonation products

The tube for spontaneous detonation (Institute of Technical Physics, Russian Federal Nuclear Center, Snezhinsk) was used to study the initiation and development of detonation in propane-air mixtures under injection of hot detonation products into them. The full picture of this phenomenon was recorded: the injection of hot detonation products into the main tube of the facility with the formation of a mixture of the starting propane-air composition with the hot products; the initiation of a local explosion in this mixture and the subsequent development of a detonation in it; detonation transfer to the region of the cold starting reactants (or detonation failure at the interface). The detonation was found to exist for an initial volume concentration of propane of 3.3 to 5%. The following critical (by the moment of the local explosion) parameters were determined: a mass fraction of hot detonation products of 6–9%, an energy input density due to product injection of 145–195 J/g, and an input energy power of 70–50 J/(g · msec). __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 100–109, May–June, 2006.     

A study of the interaction between the components of heterogeneous explosives by the electrical-conductivity method

The detonation of TNT/RDX alloys is studied by the electrical-conductivity method. The measurement technique is developed with correction for the deformation of electrodes in the explosion. The maximum electrical conductivity of pure TNT was ≈25 Ω⁻¹·cm⁻¹. The addition of RDX decreases the electrical conductivity and width of the conducting zone, which, is, apparently, connected with the formation of diamond. It is shown that the RDX particle size plays an important role. With equal mass fraction, the conductivity of the sample is several times smaller for micron particles than for millimeter particles. This fact is explained by the different degree of mixing of the detonation products of the heterogeneous-explosive components. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 97–108, September–October, 2000. This work was supported by the Russian Foundation for Fundamental Research (Grant Nos. 99-03-32336 and 96-15-96264).     

Theory of solid-state detonation

The Jouguet theory allows one to estimate the detonation velocity from the known shock adiabat of the product of a solid-state chemical reaction initiated by a shock wave. Using manganese and zinc chalcogenides as an example, it is shown that such estimates are close to experimental detonation velocities in these systems. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 108–110, March–April, 2007.     

Dynamic compaction of ultradisperse diamonds

It is established experimentally that when a powder consisting of ultradisperse diamonds is subjected loading by weak shock waves with a duration ∼10⁻⁵ sec, the mean size of the diamond particles increases by several orders of magnitude. The number of publications devoted to the shock compaction of diamond powders is not limited to those cited in this article. Besides [6, 7], we should also mention the works by D. Potter and T. Ahrens [J. Appl. Phys.,6, No. 3, 910–914 (1989)] and K. Kondo and S. Sawai [J. Am. Ceram. Soc.,73, No. 3, 1983–1991 (1990)], among others (Editor's note). All-Union Scientific Research Institute of Experimental Physics, 607200 Kremlev. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 5, pp. 136–138, September–October, 1995.     

Detonation waves in interstellar gas

In astronomy there is a large amount of observational data on the phenomenon of sequential star formation from a single molecular cloud. In this process, a cluster of stars of the same generation creates favorable conditions for the formation of stars of the next generation. A star-forming wave whose velocity is estimated to be10–30 km/sec travels over a molecular cloud of interstellar gas. In the present paper, the self-sustained star-formation phenomenon is claimed to have all features of a detonation process and the star-forming wave is treated as a detonation one. The velocities of the detonation and star-forming waves are estimated to be (∼27 km/sec) and (∼13 km/sec), respectively. Lavrent’ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 1, pp. 88–93, January–February, 1997     

Detonation properties of the synthesis gas

Investigated parameters of combustion and detonation of mixtures of the synthesis gas with oxygen and air are presented. The ratios between carbon oxide and hydrogen and between the fuels and oxidizer are varied within wide ranges. The critical energy of detonation initiation is determined. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 90–96, November–December, 2007.