Abstract:
The change of molar volumes of condensed matter in synthesis reactions in solid state is considered and the volume of the system is shown to increase in exothermic processes. A more significant increase in volume is observed at high pressures. This is reflected on the shock pressure-volume curve of the reacting mixture. Measurements of the kinematic parameters of the reacting systems show that the chemical reaction proceeds to a noticeable extent in a time of less than 10$^{-6}$ sec. Temperature measurements made it possible to establish that the reaction time was less than 10$^{-7}$ sec. A model is suggested for explaining the ultrarapid diffusion process and chemical interaction of solids. The model is based on hydrodynamic transfer (with velocities equal to the difference in the mass velocities of the reactants) of particles shattered by a shock wave. A degree of chemical conversion in the shock waves corresponds to the course of the chemical reaction over the surfaces of domains with a size of $\sim$100 $\mathring{\mathrm{A}}$.
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