Numerical study of shock compression of graphite and its conversion to diamond in conical targets

Ломоносов, И. В.; Фортов, В. Е.; Фролова, А. А.; Khishchenko, K. V.; Charakhch’yan, A. A.; Shurshalov, L. V.

doi:10.1134/1.1583826

Cited by 13 publications

(6 citation statements)

References 8 publications

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“…The latter values are located in the region between the adiabats corresponding to porosities m = 1.03, 1.07, which may be interpreted as the region of the shock adiabat of the high-pressure phase. As was demonstrated for carbon [45] (diamond is assumed to be the corresponding high-pressure phase), the experimental values lying above the region of the phase transition are close to the shock adiabat of diamond of the same initial density as the studied carbon samples. This implies that one should consider the shock adiabat for the high-pressure phase with the density lower than that of a solid material.…”

Section: Simulation Resultssupporting

confidence: 74%

Numerical modeling of carbides behavior under high-energy liading

Maevskii

2022

Technical Physics

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The results of research on modeling thermodynamic parameters ofshock-wave loading of carbides with different stoichiometric ratios arepresented. The carbides are considered as a mixture of carbon with thecorresponding component. The calculations of pressure, compression andtemperature values under shock-wave loading for solid and porous carbides inthe range of pressure values above 3 GPa are performed. The modelcalculations are compared with the known experimental results on theshock-wave loading of carbides with different porosity values. Thepossibility of modeling the behavior according to the proposed method forcarbides for which there are no experimental data at high dynamic loads isshown. Keywords: Equation of state, shock adiabat, thermodynamic equality,porous heterogeneous medium, carbides\

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Section: Simulation Resultssupporting

confidence: 74%

Numerical modeling of carbides behavior under high-energy liading

Maevskii

2022

Technical Physics

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“…As it was noted above, the phase transformation of poreless highly ordered graphite to diamond at shock compression starts at pressure > 20 GPa and ends at ~ 33 GPa [9,10]. In the p, T diagram (in compression of the substance by one SW) this process is shown by line 1, where the following regions correspond: AB to the compression of graphite, BC to the transformation into the dense phase, CD to the compression of diamond, DF to unloading of diamond.…”

Section: Production Structure Propertiesmentioning

confidence: 83%

“…Say that a striker and wall are flat. The special features of constructing a p(u) diagram when SW are generated by throwing a striker are considered in [9]. At the instance the throwable shell, which is flying at a rate of u**, strikes, a SW appears in the ampoule wall and a reflected wave in a striker.…”

Section: Production Structure Propertiesmentioning

confidence: 99%

“…Parameters of this wave are defined by the point of the intersection of the sample shock adiabat and curve 6 (point A 2 ). If the sample is highly ordered pore free graphite, according to [9,10], the pressure p 2 for the onset of the phase transformation (PhT) should be no less than 20 GPa or 33 GPa for its full completion, the rate u** should be in the range 2-2.8 km/s (if the ampoule wall and striker are made of steel). We evaluate the pressure in the powder object for u** = 2.4 km/s.…”

Section: Production Structure Propertiesmentioning

confidence: 99%

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Comparative study of phase transformations in carbon at different schemes of shock compression

Britun

Yarosh

Kurdyumov

et al. 2015

J. Superhard Mater.

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A comparative study of phase transformations in carbon-base materials at shock compression has been carried out according to two different schemes: in cylindrical ampoules with a central rod at a direct contact of explosives with the ampoule and in ampoules without the central rod with throwable outer shells. It has been found that in the shock compression on the second scheme a higher absolute out put of diamond is achieved, but as opposed to the first scheme, the shock compression products do not virtually contain lonsdaleite or dense amorphous phase. The analysis shows that in the second case the states with lower pressures but higher temperatures, which lead to a transformation of metastable phases into stable diamond, are realized.

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“…The system of MHD equations is completed by the equations of state (6) derived for metal wires at the Joint Institute for High Temperatures RAS [10]; these are the wide-range semiempirical equations based on a model [11] that takes into account the high-temperature melting and the evaporation, as well as the metastable liquid and gaseous states.…”

Section: Magnetohydrodynamic Modelmentioning

confidence: 99%

Numerical simulation of electrical explosions in megagauss magnetic fields

Oreshkin

Chaikovsky

Khishchenko

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. The paper reports on a magnetohydrodynamic simulation of electrical explosions of conductors in megagauss magnetic fields. It is shown that in a plane geometry, the time of plasma formation at the surface of a metal conductor does not depend on the rate of rise of the magnetic field and is determined by the properties of the metal; the absolute values of the magnetic field at which plasma is formed are 5±0.25 MGs for copper, 4.25±0.2 MGs for tungsten, 3.85±0.15 MGs for aluminum, and 3.6±0.25 MGs for titanium. In cylindrical geometry, the time of plasma formation does depend on the rate of field rise. IntroductionThe electrical explosion of conductors (EEC) has been studied for a long time and has a number of practical applications. An EEC mode of interest in the generation of superstrong magnetic fields and in the energy transfer, using vacuum transmission lines, is the current skinning mode [1][2][3][4]. For this mode, the time of energy delivery to the conductor is shorter than, or comparable to the time of magnetic diffusion into it. The basic processes inherent in the current skinning mode are the propagation of a nonlinear magnetic diffusion wave [5], the formation of a low-temperature plasma at the conductor surface, and the development of thermal instabilities [6,7].Nonlinear magnetic diffusion features, a speed of field penetration into a conductor are anomalously high compared to a conventional magnetic diffusion. The high diffusion speed is related to a decrease in conductivity of the metal due to its heating by an electric current. A nonlinear diffusion can occur only in a rather strong magnetic field whose induction, for the fairly often used metals, should be not lower than 250-450 kGs [1,2].

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Numerical study of shock compression of graphite and its conversion to diamond in conical targets

Cited by 13 publications

References 8 publications

Numerical modeling of carbides behavior under high-energy liading

Numerical modeling of carbides behavior under high-energy liading

Comparative study of phase transformations in carbon at different schemes of shock compression

Numerical simulation of electrical explosions in megagauss magnetic fields

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