Evaluation of Technological Capability to from Dielectric Coatings on AK6 Alloy, Using a Method of Microarc Oxidation

Abstract

The dielectric properties of coatings on AK6 alloy formed with a microarc oxidation method in two electric modes in alkaline-silicate electrolytes are estimated. It is shown that both modes, a galvanostatic mode and an arbitrarily falling power mode in alternating current circuits, make it possible to obtain coatings with a thickness of 30–60 μm, with sufficiently high electrophysical parameters: bulk specific resistance ρ_v = 3–9 × 10⁹ Ω m and dielectric strength E = 9–14 V/μm. It is established that higher values of ρ_v and E in the both modes can be achieved in the solutions of 1 g/L KOH + 6 g/L of liquid glass (LG) and 12 g/L of LG. In terms of absolute value, the parameters of the coatings formed in the mode of arbitrarily falling power exceed the same characteristics of the oxide layers formed under conditions of galvanostatic mode by a factor of 1.5–2.5.