Home – Home – Jornals – Chemistry for Sustainable Development 2009 number 6

The zones of normal-tangential indenting (N-TI) of the single crystals of apatite, quartz and lithium fluoride were examined by means of scanning and high-resolution electron microscopy. The texture, structural and phase transformations thus detected were conventionally related to the "deformation" and "diffusion" processes of plastic deformation. Two levels of structural transformations were revealed in the zones of N-TI in signle crystals; a sharp boundary between them occurs at the strain equal to the theoretical strength limit (σ_tsl). In the upper zone of scratches within the strain range from microhardness value H_ц to the σ_tsl value, the substance undergoes profound structural and phase transformations with the formation of the amorphous state, "paracrystalline", "liquid crystal" and "two-dimensional" nanoparticles. The substance in the zone of scratches is a model of mechanically activated substance. In the bed of scratches at the strain below σ_tsl we observe fragmentation of single crystals with the formation of blocks and steps; this is a model of the grinding process. A wave model is proposed for the transformation of the input mechanical energy for indention with the specific power approximately equal to 3 · 10¹¹ J/(m³ · s), which is close to the level of atom bond strength in the activated zone of N-TI. As a result of excitation of chemical bonds, phase and structural transformations occur in the activated zone of N-TI.