Macrokinetics of Mechanosynthesis in Solid-Gas Systems. I. Mathematical Simulation

Abstract

A mathematical model for mechanosynthesis in solid-gas systems is constructed which includes the equations of mechanical-reactor heat balance, grinding, the excess-energy dynamics in the condensed substances, which determines the effect of mechanical activation on the chemical-reaction rate, and the reaction kinetics. A brief analysis of the model is presented. A description is given of two simplified models of independent significance derived from the general model, which can be studied by analytical methods. Synthesis in a preactivated system is studied in detail. Relations determining the characteristics of the synthesis are obtained. The accuracy of the analytical estimates is verified by numerical simulation.

Effect of phase transformation on nonisothermal synthesis in mechanically activated heterogeneous systems

“…The changes in the excess energies of the reagents and the product are determined by the equations [1][2][3][4][5] …”

“…The macrokinetics of such processes was considered in [3][4][5]. In the course of heating and chemical conversion of the reacting mixture, excess energy relaxation is assumed to follow two paths [6]: "normalization" of the structure and chemical reaction.…”

Macrokinetics of Mechanosynthesis in Solid-Gas Systems. II. Experimental Studies. Analysis of Results

“…(14) in [1] one can estimate the rate of excessenergy supply to the reactant (the activation rate of the reactant) in a linear approximation (see straight line 2 in Fig. 3).…”

“…Making relation (40) from [1] dimensionless and taking the logarithm of it, we obtain the straight-line equation…”

“…Experimental studies of mechanochemical synthesis in the titanium-nitrogen system were performed to validate the current concepts of the macrokinetics of mechanosynthesis in solid reactant-reactive gas systems and the adequacy of the mathematical models constructed in [1]. The choice of this system has a practical meaning since the products of mechanosynthesis in it are ultrafine powders with nanocrystalline structure, which are promising for the design of new materials [2].…”