Influence of the Modes of Plasma-Electrolytic Oxidation on the Dielectric Properties of Coatings on D16T Alloy

Abstract

We study the influence of plasma-electrolytic oxidation (PEO) of deformed D16Т alloy on the dielectric properties of PEO coatings in alkaline-silicate electrolytes. It is shown that the increase in the duration of oxidation from 1 h to 2 h under the conditions of arbitrarily falling power (AFP) and alternating current leads to worsening of the parameter ρv by a factor of 2–2.5 and a decrease in the electric strength E by 30–40%. In the galvanostatic mode, under the conditions of identical thicknesses of the coatings, the electrical parameters insignificantly decrease as the anode current increases within the range 5–15 A/dm2 . At the same time, their dependence on the composition of electrolyte is more pronounced. It is known that the best characteristics of volume resistance ρv = 3.3–4.3·109 Ω·m and E = 10–13 V/μm in both modes are attained for the alkaline-silicate (1:6) and silicate (0:12) solutions of electrolytes. The absolute values of characteristics of the coatings formed under the conditions of AFP are 1.2–1.9 times higher than the similar characteristics of oxide layers formed in the galvanostatic mode.