Evaluation of dielectric properties of micro-arc coatings on deformable aluminum alloys

The dielectric properties of MDO coatings on deformable alloys AK6 and D16T formed on an alternating current in the regime of an arbitrarily falling power in alkali-silicate solutions have been studied. It is shown that the increase in the oxidation time in twice (from 1 to 2 hours) leads to a decrease in the index ρ_v in 2-5 times, depending on the grade of the alloy and the solution composition. It has been established that the best dielectric values ρ_v=(4...9) centre dot 10⁹ Om centre dot m, E=13...14 V/μm are provided by coatings on both alloys formed in solution 1 g/l KOH + 6 g/l W.G. (water glass). A small advantage in terms of the value ρ_v of 2 to 2.5 times with comparable thicknesses have MAD layers on the alloy AK6.