Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 5, pp. 635639.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © Zh.I. Bespalova, I.N. Panenko, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 5, pp. 686690.
AND INDUSTRIAL INORGANIC CHEMISTRY
Formation of Micro-Arc Coatings on the Surface of D16
Zh. I. Bespalova and I. N. Panenko
Novocherkassk Polytechnic Institute, South-Russian State Technical University, Novocherkassk,
Rostov-on-Don oblast, Russia
Received August 24, 2012
Abstract—Results of a study of how optically black coatings are formed by micro-arc oxidation on the surface of
D16 aluminum alloy are reported. Coatings with high optical properties were obtained on this alloy in the pulsed
anodic-cathodic mode of treatment in the electrolyte composition developed in the study.
At present, one of the most promising ways to
fabricate new functional coating on the surface of valve
metals is by the micro-arc oxidation (MAO) method.
The name of this technique has been changed more than
once in attempts to reﬂ ect a particular concept of its
mechanism: plasma-electrolytic oxidation , anodic-
spark electrolysis , and microplasma oxidation .
In MAO, microplasma discharges create conditions
for formation of high-temperature, insoluble in a
given electrolyte chemical compounds based on the
elements contained in a metal being processed and in
the electrolyte. In recent years, great attention has been
paid to formation of optically black functional coatings
under microplasma discharges [4–6], because just
these coatings constitute an important part of modern
information displays and promising temperature-control
coatings. Analysis of the available data [4–7] suggests
that optically black oxide-ceramic coatings are mostly
deposit from phosphate electrolytes in the galvanostatic
mode at rather high dc current densities of 4–20 A dm
The coatings have not-too-high absorption coefﬁ cients
(~90–92%) and only for visible light, relative to the MgO
reference at wavelengths in the range 500–700 nm. In
this context, it was of interest to examine the possibility
of obtaining optically black coatings with high optical
properties from silicate-alkaline electrolytes.
The goal of this study was to obtain optically black
coatings with high optical and functional properties on
the surface of D16 aluminum alloy by the micro-arc
The micro-arc oxidation was performed on an
installation comprising a technological current source,
a reversible thyristor converter that was computer
controlled with special software and delivered to a
sample being oxidized anodic-cathodic pulse packets
with variable amplitude and width. Te oxidation was
performed in stainless steel bath with a water-cooling
jacket. The bath casing served as the counter electrode.
The electrolyte was agitated with a magnetic rabble, its
temperature was automatically maintained at 30 ± 3°C.
The coatings were deposited with asymmetric pulsed
current with anodic and cathodic pulse packet widths
of 50 and 40 ms, respectively, with an interval of 10 ms
between these packets, at a ratio of 1.1 : 0.9 between
the average anodic and cathodic currents. The anodic
and cathodic voltages were 200–250 and 50–80 V,
The study made it possible to develop a composition
of an electrolyte constituted by three solutions in which