The synthesis of detonation diamonds from a mixture of RDX labeled by C 14 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)%.At present, the synthesis and properties of diamonds produced from mixtures of high explosives (HEs) with various carbon-containing materials (graphite and soot) in a detonation wave have been studied fairly thoroughly [1][2][3]. It has been assumed that diamond is formed from the carbon additive by a phase transition. However, the discovery of the synthesis of ultrafine diamonds (UFDs) with a high yield [4,5] from the carbon of HE molecules indicates that this approach is ambiguous and that further analysis of this phenomenon is required. The tracer element method is the most convenient for such studies. It provides a direct estimate of the degree of participation of the carbon of HEs and the additive in diamond formation.The present paper describes the synthesis of detonation diamonds from 85.6/14.4 RDX/soot mixture using RDX labeled by C 14 isotope. The charge was manufactured from P-803 soot with a specific surface area of 14-18 m 2 /g and phlegmatized RDX [containing 5.0-6.5% (by weight) phlegmatizer]. The mixture of the components was carefully stirred. The charge of mass 105 g and diameter 40 mm was produced by pressing at a specific pressure of 1800 kg/cm 2 and was ignited in an explosive chamber of volume 0.175 m 3 in nitrogen at an initial pressure of 0.8 MPa. Diamonds were extracted from the collected explosion products by boiling in a mixture of sulfuric and nitrogen acids until the appearance of the characteristic light gray color. After washing from acids, extraction from the suspension by centrifuging, and drying, the sample was analyzed for moisture and the contents of total carbon, diamond, and unburned additives. The isotopic composition of the starting RDX and the diamonds was studied on a LS-230 (Beckman) liquid scintillation beta spectrometer. The mass fraction of the diamond formed from the carbon of RDX was calculated from results of specific radioactivity measurements and chemical analysis.The data showed that (24.7 ± 3.4)% of the synthesized detonation diamonds formed from the carbon of RDX molecules. Actually, this fraction of diamonds contain UFDs. It depends on the HE composition and the charge density and can be even larger if TNT or its mixtures with RDX or HMX are used as the explosive for loading the carbon material. In this connection, it should be noted that the use of the percentage of conversion of the carbon additive to diamond to describe the results of detonation experiments is correct only in the absence of the ultrafine fraction in the detonation diamonds separated from synthesis products. Otherwise, it is necessary to use the other parameter: the yield of diamonds with respect to the mass of the HE charge or any other parameter that takes into accou...
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.Key words: detonation synthesis, ultrafine diamond.At present, ultrafine diamonds (UFDs) are produced by detonation of high explosives (HEs) using TNT mixtures with more powerful HEs -sensitizers. This is motivated by the availability of TNT, handling safety, the possibility of manufacturing charges by different methods, and a number of other factors. The addition of sensitizers to TNT is dictated by the necessity of increasing the detonation characteristics because pure TNT has not too high detonation parameters, resulting in a low yield of UFDs. In this connection, the most extensive studies have been performed of the use of RDX, HMX, and PETN as sensitizers, for which the optimum contents in mixtures were determined [1][2][3].Experiments have shown that the maximum yield of UFDs (three to four time higher than the yield of UFDs from pure TNT) is achieved at a sensitizer content of 40-50%. In this case, most of the diamond particles is formed from the TNT carbon. Much less UFDs are synthesized from the carbon of the sensitizer [4,5], which affects the total amount of the resulting diamonds. Therefore, to increase the yield of UFDs, it is important to study the synthesis of TNT mixtures with other sensitizers with various structure and properties.
The effect of the particle size of HMX in alloys with TNT on the synthesis of nanodiamonds in a detonation wave was studied experimentally. Mixtures with a TNT content of 40 to 90% and the specific surface area of HMX varied in the range of 5-510 m 2 /kg were investigated. For all mixtures, an increase in the particle size of HMX was found to lead to an increase in the yield of nanodiamonds with the maximum yield shift toward alloys with increased TNT content. The results are explained using a model based on the absence of thermodynamic equilibrium between the components of the heterogeneous explosive during detonation.
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