ELECTRICAL STRENGTH OF OXIDE COATINGS FORMED BY THE METHOD OF MICRO-ARC OXIDATION

Abstract

The paper presents the results of studies of the structure and properties of coatings on aluminum alloys D16, AMg6 and AL25. The features of the surface morphology of aluminum-based alloys after their MAO treatment are revealed. A study of the kinetics of coating thickness formation showed that an almost linear dependence of the thickness on the time of oxidation is realized.

It was established that the phase composition of the coatings is different for different alloys: the main phase in the coating on D16 alloy is the α-Al₂O₃ phase (60–70 %), on the AMg6 alloy –                         γ-Al₂O₃, on the AL25 alloy – Al₂O₃ • 2SіO₂ mullite (60–70 %). The dependence of electric strength on the structural state is shown.

It was found that the X-ray amorphous state of the MAO coatings allows one to achieve a relatively high electric strength (E = 10 V / μm) at a high rate of formation of such coatings. This makes this technology the most promising for producing coatings with high electrical insulation.