Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 4, pp. 575−579.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © M.S. Vasil’eva, V.S. Rudnev, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 4, pp. 557−561.
AND INDUSTRIAL INORGANIC CHEMISTRY
The Effect of Annealing on the Composition and Morphology
of the Surface of Ni-containing Oxide Layers on Titanium
Formed by Plasma-Electrolytic Method
M. S. Vasil’eva and V. S. Rudnev
Far-Eastern Federal University, Vladivostok, Russia
Institute of Chemistry, Russian Academy of Sciences, Far-Eastern Division, Vladivostok, Russia
Received August 19, 2011
Abstract—The effect of annealing temperature on the elemental composition and morphology of the Ni-containing
coatings formed by plasma-electrolytic oxidation in sodium silicate electrolyte suspension with and without sodium
oleate was studied in the range 750–850°С.
Supported nickel-containing catalysts are widely
used in different catalytic processes [1
5]. The different
methods (impregnation, codeposition, sol-gel synthesis,
and other methods) are used for their deposition . The
electrochemical methods, including plasma-electrolytic
oxidation (PEO), can be applied in the case of the sup-
ports made of metals and alloys . The latter method
allows single-stage deposition of functional oxide coat-
ings on shaped metallic articles during reasonably short
time (from several to tens of minutes) at temperature
not exceeding 50°С. These compositions are resistant to
thermal shock and their metallic support has high thermal
and electrical conduction properties.
Plasma-electrolytic oxidation in electrolyte suspension
is a method of the formation of oxide surface structures
of complex composition [8
12]. The method was applied
for deposition of coatings containing particles of Аl
, МgО, Сr
, and ZrО
and ﬁ nely disperse
glass particles on valve metals. Previously, PEO in so-
dium tetraborate or sodium silicate electrolyte suspen-
sions was used to obtain coatings containing dispersed
particles of MnO
, NiO, or Mn
. It was found
that the amount of transition metals incorporated into
the coatings in sodium silicate electrolyte is several-fold
higher than in tetraborate electrolyte. The addition of sur-
factants to a nickel oxide suspension increases the nickel
incorporation from 3.2 to 14.3 % and changes the surface
morphology of nickel-containing oxide coatings .
The changes in the composition and surface morphology
of nickel-containing coatings formed in the electrolyte
containing sodium oleate lead to the increase in their
catalytic activity in CO oxidation within 200–500°С. It
may be suggested that the above coatings will be active
in other catalytic reactions, including high-temperature
reactions. The possibility of using PEO coatings in high-
temperature catalysis will be determined primarily by
their thermal stability.
The study is concerned with thermal behavior of the
elemental composition and morphology of Ni-containing
oxide coatings on titanium formed by plasma-electrolytic
oxidation in electrolyte suspensions including those con-
taining sodium oleate.
Plasma-electrolytic coatings were formed on titanium
(VT1-0) wire (diameter 0.2 cm). The samples were pol-
ished in a mixture of acids (HF : HNO
= 1 : 3) at 60–80°С
for 2–3 s, washed with distilled water, and dried in air.
The electrochemical cell was in the form of a 1-l glass
vessel. The oxide coatings were formed galvanostati-
cally on anodically polarized titanium immersed into the