SHOCK-ASSISTED SOLID  SOLID SYNTHESIS: STRUCTURE OF REACTION ZONE S. V. Buravova, Yu. A. Gordopolov, N. A. Denisova, and I. V. Saikov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Moscow, Russia

1. M.F.Gogulja, I.M.Voskoboynikov, A.J.Dolgoborodov, et al. Interaction of sulfur and aluminum behind shock waves. Chemical Physics, 1992,v. 11, №2, (A method of optical pyrometry) Dependence of brightness temperatures in time. Р~34.6 (18.2) GPа. Profile of pressure in the indicator liquid ССl, for samples 55 Аl/S (1 and 2); sulfurs (3); aluminum (4) At the beginning stages of measurements, the temperature decreases. And in samples with large particles of aluminum the temperature rise is observed. Al/S

2. M.F.Gogulja, M.A.Brazhnikov, About characteristic times of chemical reactions in heterogeneous systems at dynamic loading, Chemical Physics, 1994, v. 13, 11, At the first moments of record, high level of radiation shows hot spots during shock loading solid – solid heterogeneous system. Change of intensity of radiation (=740 nanometers) pressed powder Al on contact border with LiF, 1-large, 2 – fine. Change of intensity of radiation (=740 nanometers) the pressed powder of sulfur on contact border with LiF (1) and glycerin (2)

3. SULFIDES. S.S.Batsanov, M.A.Brazhnikov, G.V.Simakov, I.I.Maxim. Physics of burning and explosion, M.F.Gogulja, I.M.Voskoboynikov, A.J.Dolgoborodov, N.S.Dorokhov, M.A.Brazhnikov, Chemical physics, 1991, v. 10, 3, p. 420 ; т 30, №3, pp Degree of transformation Μg/S (43/57) at pressure 24 GPа Al/S (55/45) at pressure 27 GPа. Effective brightness temperatures Μg/S(24 GPа) Al/S (27) -3000К, Ti/S (28 GPа) К Sn/S (at pressure GPа) Time of chemical reaction is comparable with resolving time of a pyrometer ( nanoseconds).

4. Silicides. N.N. Thadhani, R.A. Graham, T. Royal, E. Dundar, M.U. Anderson and G.T. Holman, Shock-induced chemical reaction in titanium- silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis., Appl. Phys. 1997, v. 82, N 3, p System Ti+Si. Reaction occurs only in mixtures containing particles of the average size (at pressure 1.5 GPа). Mixtures with large and fine particles Systems Mo+Si and Nb+Si. Reactions are not initiated at pressures up to 7 GPа..

5. Ni+AL D.E.Eakins, N.N. Thadhani. Discrete particle simulation of shock wave propagation in a binary Ni+Al powder mixture, J. Appl. Phys., v. 101, (2007) A synthesis takes place at 8-10 GPА, it exceeds yield strength. Under the conditions a shock wave is split into an elastic precursor and plastic wave Shock wave propagation In mixtures with 80 % and 60 % density, the high pressure zone moves after the precursor following to wide area low amplitude pressure to networks of elastic harbingers. The distance between them is 300 micron for 80 % density, 100 microns for 60 %, and completely absent for 45 % density.

6. S.S. Batsanov, Features of the solid - solid transformations initiated by shock waves, Successes of Chemistry, 2006, v. 75, (7), pp. 669 N.N. Thadhani, R.A. Graham, T. Royal, E. Dundar, M.U. Anderson and G.T. Holman, Shock-induced chemical reaction in titanium-silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis, Appl. Phys. 1997, v. 82, N 3, p Sn+S 15 GPа S+Al 15 GPа Ni+Al GPа Nb+Si 20 GPа Ti+Ni 3.2 GPа Al+Fe 2 O 3 5 GPа Sn+Te 45 GPа Ti+C 15 GPа Ti+Si 1.5 GPa Cu + Al 32 GPа Fe+S 28 GPа It was experimentally proved that ( 1)Superfast chemical reaction takes place; (2) reaction is initiated in local the “hot spots”; (3) degree of transformation is insignificant (4) shock wave is split into an elastic precursor and plastic wave

7. Low – velocity wave regime of explosive transformation. A.F.Beljaev, V.K.Bobolev, A.I.Korotkov, A.A.Sulimov, S.V.Chujko. Burning transition of the condensed systems in explosion Both shock wave and reaction zone (low -velocity detonation) propagate stationary up to diameters of a charge Figure I illustrates transition of low – velocity detonation into a high-speed one depending on the charge diameter (tetryl = 0.92) Figure II illustrates dependence of a low – velocity detonation on density (ten, plexiglass capsule)

8. Profile of mass velocity for the case low – velocity detonation in high density charge Low-velocity regime of explosive transformation with subsonic speed is caused by movement of the plastic wave without jump at the front. The plastic wave in trotyl extends with subsonic speed. The basic role of a metallic capsule is pressure maintenance at the certain level. Mechanical activated mixture of Al + teflon has the same profile of mass velocity

9.Wide zone of reaction is the basic feature of low-velocity detonation. The heat release is % of normal detonation energy Chemical reaction arises behind a compression wave with a significant delay. The distance between fronts is 40 mm at 1400 km/s and does not vary in time. For a charge with high density the distance between fronts is mm at 1000 km/s

10. Area of low-velocity detonations propagation is 7-15 kbars. This is an area where the shock wave is split on elastic and plastic waves. Oscillogram of mass velocity in the pressed trotyl. a - shock wave (10 kbar); b - elastic and plastic wave (р=5 kbar)

11. Similarity and distinction of reactions during synthesis and decomposition. (1) Reaction occurs in hot spots (2) Not full degree of transformation during synthesis and heat release at decomposition (3) Shock wave slits on elastic and plastic ones Main distinctions Ultrafast reaction (nanoseconds) during synthesis and the slow development of the reaction during low – velocity detonation (up to dozens micro seconds)

It is necessary to study structure of a full reaction zone including afterburning one during solid – solid synthesis 12. Conclusion The aim of the work is to attract attention to the problem

13. Gogulja M.F., Бражников. М.А. About characteristic times of chemical reaction in heterogeneous systems at dynamic loading. Chemical physics, 1994, т. 13, N 11, Unique work. Time measurement made 6 microns. After sharp decrease of temperature growth of temperature that testifies to afterburning process takes place. Change brightness temperatures of the sample on border of section, 1-3 stoichiometry 43/57; /37; 1,4 (LiF); 2 - (H 2 O); 3, 5 - ПММА; the shaped line is received on =720 nanometers; continuous - on =420 nanometers. Mg/S