Chuvash State University (Cheboksary, Russia):

I. E. Illarionov, Dr. Eng., Prof., Head of the Chair “Material Science and Metallurgical Processes”, e-mail: tmilp@rambler.ru

Siberian Federal University (Krasnoyarsk, Russia):

T. R. Gilmanshina, Cand. Eng., Associate Professor, e-mail: gtr1977@mail.ru
A. A. Kovaleva, Cand. Eng., Associate Professor
N. A. Bratukhina, Associate Professor

How the properties of protective coatings form is a complex mechanism that is yet to be studied. Because of the lack of such understanding, researchers predominantly rely on an empirical method to create protective coatings that would offer a necessary performance. In quality terms, the process of building a protective layer involves two stages: Stage 1 — properties formed during preparation in liquid state; Stage 2 — structure formed while the coating is drying. Properties start to form even during preparation when liquid protective coatings experience such processes as ion adsorption, electrocapillary and electrokinetic phenomena, material and energy transport through colloid systems, electrostatic interaction between colloidal particles. These processes govern the overall future performance and efficiency of protective coatings. The electrical double layer and the potentials arising in it play a major role in these processes. This research aims to understand the properties of aqueous suspensions with natural and mechanically activated graphites. The graphite was activated in an AGO-2 planetary centrifugal mill. The findings show that the sedimentation stability of suspensions and coatings is governed by the size of the electrical double layer in graphite particles. Due to mechanical activation, the electrical double layer of graphite grows from 0.3 to 0.4 mV, while the sedimentation stability after 24 h of settling rises from 66 to 76% and from 87 to 97% with the concentrations of graphite being 30 and 50 w/w per 100 w/w of water, correspondingly. Accumulation of structural defects in graphite particles contributes to the growth of the electrical double layer at the surface of graphite particles. This makes the contact area of the interacting phases — i.e. graphite and water — larger and produces active nuclei on the freshly produced surface.

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