Mechanochemistry and mechanical activation

In studies of the influence that a stress field caused by the mechanical deformation of a solid has on its reactivity, two possible limiting cases are commonly considered: if the relaxation time of the stress field is shorter than the chemical reaction time, then mechanochemical reactions are concerned. In the opposite case, we are dealing with mechanical activation. In the present work, the emphasis is on the mechanical activation of one-component and polycomponent systems. The second part of this presentation covers the defects occurring during activation in one-component systems: changes in the concentration of point defects, dislocations, anomalous distribution of point defects in crystalline lattices, the formation of quasicrystalline structures, and the influence of these defects on solid-state transformations (polymorphous transitions, thermal decomposition, reduction, chemical dissolution). The mechanical treatment of mixtures containing two or several components involves additional problems related to the fragmentation, mixing and compacting of particles. The main processes occurring at the interface are considered: a) formation of solid solutions followed by a chemical reaction, b) formation of mechanocomposites when no mixing at the atomic level or chemical interaction take place. The main requirements for the design of mechanical activation equipment are considered for both one-component and mixed systems.