REC «Mekhanobr-Tekhnika» (St. Petersburg, Russia):

Cherkasova M. V., Leading Researcher, Candidate of Engineering Sciences, cherkasova_mv@mtspb.com
Arsentiev V. A., Chief Researcher, Doctor of Engineering Sciences, ava@mtspb.com
Ustinov I. D., Chief Researcher, Doctor of Сhemical Sciences, ustinov_id@mtspb.com

The study shows that the fine grinding process proceeds simultaneously with particle aggregation. This happens when the effects of surface forces exceed the effects of gravitational forces generated by external (gravitational, centrifugal) fields. The size reduction and aggregation processes, in this case, are in a dynamic equilibrium, and longer grinding times fail to produce finer particles for the material being ground. Since multiple deforming effects are required to reduce the size of metal particles, relaxation of microcracks on the surface of these particles in the intervals between mechanical impacts must be prevented. Fine grinding of metal particles without the use of substances to prevent microcrack relaxation is therefore virtually impossible. In view of the fact that the size of microcrack defects that occur in metal particles during shear deformations is only 0.3–0.6 nm due to the steric factor, a limited number of available substances may only be used for propping these defects and preventing their relaxation. Respective propping components may be obtained from gases such as hydrogen, helium, oxygen, carbon dioxide, and ammonia, or solids (or their solutions) such as urea, ammonium salts, polymethyl methacrylate, polystyrene, polyethylene, etc. The study shows that fine grinding of metals may be intensified through the use of two reagents with different process impact mechanisms: a grinding aid to facilitate the formation of defects at the initial stages of exposure of the particles to be ground and dispersants for disaggregation of the reduction products of these particles.

The study was carried out under the grant issued by the Russian Science Foundation (project No. 20-79-10125).

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