INFLUENCE OF THE MODES OF PLASMA-ELECTROLYTIC OXIDATION ON THE DIELECTRIC PROPERTIES OF COATINGS ON D16T ALLOY

摘要

We study the influence of plasma-electrolytic oxidation (PEO) of deformed D16. 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 rho(v) 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/dm(2). At the same time, their dependence on the composition of electrolyte is more pronounced. It is known that the best characteristics of volume resistance rho(v) = 3.3-4.3.10(9) Omega.m and E = 10-13 V/mu m 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.