Regularities of the electrochemical treatment of aluminium and its alloys in the solutions of orthophosphoric acid with the potassium dichromate additives

doi:10.26565/2220-637X-2012-21-31

T. S. Lukashuk V.N. Karazin Kharkiv National University
Vasilyi I. Larin V.N. Karazin Kharkiv National University
Anna P. Radchenkova V.N. Karazin Kharkiv National University
S. V. Pchenicna V.N. Karazin Kharkiv National University

DOI: https://doi.org/10.26565/2220-637X-2012-21-31

Keywords: aluminum, aluminium alloys, kinetics, dissolution, ionization, passivation

Abstract

The kinetic regularities of the processes of aluminium electrochemical treatment in solutions of orthophosphoric acid with potassium dichromate additives are investigated in this work. It is determined, that the kinetics of these processes depends on the ratio of the concentration of H₃PO₄ to the concentration of K₂Cr₂O₇: with the increase of the coefficient K=c_H₃_PO4/c_K₂_Cr2_O7 the aluminium passivation intensifies and, on the contrary, the aluminium ionization intensifies with K value reduction. The influence of the Cr⁶⁺ / Cr³⁺ ratio as well as the amount of the dissolved aluminium on the kinetics of ionization / passivation reactions at electrochemical processing of aluminium are investigated. The optimal K ratio for electrolytes of etching and oxidizing are proposed.

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