Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 8, pp. 11471152.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.S. Rudnev, A.A. Vaganov-Vil’kins, P.M. Nedozorov, T.P. Yarovaya, N.M. Chigrinova, 2012, published in Zhurnal Prikladnoi
Khimii, 2012, Vol. 85, No. 8, pp. 12011207.
AND INDUSTRIAL INORGANIC CHEMISTRY
Formation of Oxide Layers Modiﬁ ed
with Polytetraﬂ uoroethylene or Graphite on Aluminum
and Titanium Alloys by Plasma Electrolytic Oxidation
V. S. Rudnev
, A. A. Vaganov-Vil’kins
, P. M. Nedozorov
T. P. Yarovaya
, and N. M. Chigrinova
Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
Far Eastern Federal University, Vladivostok, Russia
Belarusian National Technical University, Minsk, Belarus
Received March 6, 2012
Abstract—For one-stage formation of coatings containing polytetraﬂ uoroethylene or graphite, it was proposed
to use Na
+ NaOH aqueous electrolyte containing siloxane–acrylate emulsion and dispersed powders of
polytetraﬂ uoroethylene or graphite. The phase and elemental composition and surface morphology of the formed
coatings were determined. It was shown that the introduction of polytetraﬂ uoroethylene markedly increases the
hydrophobic and wear-resistant properties of coatings.
Introduction of polytetraﬂ uoroethylene (PTFE) or
graphite into oxide coatings formed on aluminum and
titanium alloys by plasma electrolytic oxidation (PEO),
which is also known as microarc oxidation (MAO),
leads to an increase in their protective properties [1–4].
Polymers and graphite are introduced into electrolytes
[1–3] or applied to the surface of preliminarily formed
oxide coatings by tribological or deposition methods [4,
5]. In the presence of the above additives, homogeneity
of aqueous electrolytes becomes unstable. As in template
synthesis , the use of electrolyte emulsions, in which
dispersed particles of polymers, graphite, and other solid
compounds are stabilized in the micelles of the emulsi-
ﬁ ers, is the possible way to solve the above problem.
We studied the regularities of formation of PEO coat-
ings on aluminum and titanium in aqueous electrolytes
in the presence of dispersed PTFE or graphite particles
and a siloxane-acrylate emulsion in the base electrolyte.
Polymer- and graphite-containing oxide layers were
formed on 20 × 20 × 0.5-mm samples made of AMg5
aluminum and VT1-0 titanium alloys. Sample preparation
prior to oxidation, electrochemical cell, power source,
and determination of phase and elemental composition
and coating thickness were similar to those described
previously . The oxide coatings were deposited in the
galvanostatic mode at a current density of 0.05 cm
20 min. The base electrolyte of composition 10.6 g L
O + 2 g L
NaOH was prepared from
distilled water and chemically pure grade commercial
reagents. Electrolyte composition was similar to that
described in . As emulsifier was used KE 13-36
commercial siloxane–acrylate emulsion produced at
an Astrohim Limited Responsibility Company, Russia
(Fig. 1). We used inequigranular PTFE powder of the
Forum brand (Russia), grain size of main fraction about
1 m. Dispersed graphite particles with average sizes less
than 50 m were obtained from graphite rods by grinding
and following separation of coarser particles by sieving
(sieve mesh 50 × 50 m).
Working electrolytes were prepared in two stages.
First, 100 mL of siloxane–acrylate emulsion was mixed
with 50 g of PTFE powder or 10 g of graphite. The mix-
ture was thoroughly stirred with a magnetic stirrer for
at least 30 min till wetting of powder particles with the