Influence of the Modes of Plasma-Electrolytic Oxidation on the Dielectric Properties of Coatings on D16T Alloy
- PDF / 441,482 Bytes
- 6 Pages / 594 x 792 pts Page_size
- 108 Downloads / 197 Views
INFLUENCE OF THE MODES OF PLASMA-ELECTROLYTIC OXIDATION ON THE DIELECTRIC PROPERTIES OF COATINGS ON D16T ALLOY Yu. G. Gutsalenko,1 E. К. Sevidova,1, 2 and І. І. Stepanova1
UDC 621.791.75
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 ρ 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 ρ v = 3.3– 4.3 ⋅10 9 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. Keywords: plasma-electrolytic oxidation, dielectric properties, PEO coating, electrolytes.
Introduction Plasma-electrolytic oxidation (PEO), as a kind of surface treatment of valve metals is investigated sufficiently comprehensively and the technologies based on the use of this treatment are implemented in the engineering practice. Most often, PEO is used in the case of treatment of aluminum and its alloys for the formation of coatings with high wear, heat, and corrosion resistance on their surfaces and numerous scientific and applied investigations are devoted to the optimization of these processes [1–4]. The amount of information about the dielectric properties of PEO coatings is much smaller and their parameters (specific volume resistance, electric strength, etc.) are characterized by a broad range of values [5, 6]. These coatings are dielectrics that can be used as low-voltage insulating materials [7]. The application of PEO coatings in the metal cases of diamond grinding discs for their electric insulation from the machine mainframes, which is a necessary condition for electrophysicochemical grinding [8, 9], can be regarded as a promising possibility [8, 9]. Since at present there are no general principles for the choice of conditions required for the formation of PEO coatings (compositions of electrolytes, modes of electrolysis, etc.) with required structures and properties, it is customary to determine them experimentally for each specific treated metal. The aim of the present work is to study the influence of the main factors of plasma-electrolytic oxidation on the dielectric properties of coatings formed on D16T alloy and to determine the rational modes of their formation. 1 2
“Kharkiv Polytechnic Ins
Data Loading...
