EMT 28 P Microarc oxidation in the course of pulse polarization in the galvanic-dynamic mode
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GORDIENKO, P., DOSTOVALOV, V., ZHEVTUN, Ivan, SHABALIN, I.. EMT 28 P Microarc oxidation in the course of pulse polarization in the galvanic-dynamic mode. In: Materials Science and Condensed Matter Physics, Ed. 6, 11-14 septembrie 2012, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2012, Editia 6, p. 297. ISBN 978-9975-66-290-1.
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Materials Science and Condensed Matter Physics
Editia 6, 2012
Conferința "Materials Science and Condensed Matter Physics"
6, Chișinău, Moldova, 11-14 septembrie 2012

EMT 28 P Microarc oxidation in the course of pulse polarization in the galvanic-dynamic mode


Pag. 297-297

Gordienko P.1, Dostovalov V.2, Zhevtun Ivan1, Shabalin I.1
 
1 Institute of Chemistry, Far East Division, Russian Academy of Sciences,
2 Far East Federal University, Vladivostok
 
Disponibil în IBN: 27 martie 2020


Rezumat

Formation of defect-free oxide layer on metals at anodic polarization is only possible to certain potentials. In the 1950-70s, it was shown that the breakdown phenomenon should be used to form the surface layers complex in composition. The computer system allowing to specify conditions of the electrochemical process – rate of potential growth, cure time at specified potentials, repetition frequency of polarizing impulses and relative pulse duration - was developed. In order to obtain data of electrophysical properties of formed oxide layers and kinetics of their formation, the oxidizing process was realized in the course of impulse galvanic-dynamic polarization of the electrodes under study for which purpose the adjustable reactive load is connected in series with the electrochemical cell connected to the thyristor power source. This was allowed, within the time interval of the polarizing impulse (fractions of millisecond), to record currents and voltages at the polarized electrode, to look through the time and current-voltage dependences of oxide layers, to regulate the energy consumption and to change the morphology of coating formation. For the first time, it was experimentally shown that the electric breakdown takes place initially in the metal-oxide-electrolyte system at critical potentials and, then, it changes into the thermal one resulting in destruction of the oxide layer (Fig.1). The recorded current-voltage characteristic of the prebreakdown state of metal-oxideelectrolyte system (in a time of impulse action) complies with the classical concepts of the breakdown mechanism development, but, in the case under consideration, the majority carriers – electrons – fall within the depletion region of the space charge of oxide at critical strengths of electric field as a result of O2- discharge formed at the oxide surface on the part of electrolyte and this, in turn, results in oxygen release at the anode. In the report, the experimental data concerning the formation of coatings at titanium in the phosphatic electrolyte will be presented.Fig. 1 Dependence of current, voltage on film (Uпл) and input polarizing impulse on time (a) and current voltage characteristic (CVC) of oxide film (b). Sample 420-17, τф = 16.79 s, Iа = 1.13 А·s; Iк = 0.051А·с; Pa = 23.96 W·s; Pк = 0.49 W·s;