Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 5, pp. 826−830.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
O.I. Kuntyi, G.I. Zozulya, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 5, pp. 775−778.
AND CORROSION PROTECTION OF METALS
Morphology of Dispersed Zinc Deposited by Pulsed Current
in a ZnCl
O. I. Kuntyi and G. I. Zozulya
Lviv Polytechnic National University, Lviv, Ukraine
Received August 11, 2009
Abstract—Morphology of dispersed zinc deposits produced by pulsed electrolysis from aqueous ZnCl
solutions was studied.
The conﬁ guration of representative particles is
among the main characteristics of a powder in powder
metallurgy [1, 2], catalysis , and composite materials
. With the prospects for application of electrolytic
dispersed metals taken into account , it is important
to obtain these metals with a prescribed morphology
in the stage of cathodic formation of the deposit. An
effective method for synthesis of particles with various
conﬁ gurations is pulsed electrolysis, which has been
shown for the examples of deposition of copper [6, 7]
and silver  powders.
The present study, concerned with the effect of
the pulsed electrolysis mode on the morphology of
dispersed zinc, continues the systematic analysis of the
electrochemistry of dispersed metals .
Zinc was deposited in a 50-cm
thermostated glass electrolyzer in solutions of 0.05
+ 0.5 M NH
Cl and 0.1M ZnCl
+ 1.0 M
Cl at 20°C. As the working electrode served the
edge of a copper rod 10 mm in diameter with a side
surface insulated with a ﬂ uoroplastic tape. Prior to
any experiment, the working surface of the electrode
was trimmed with emery paper and then washed
with isopropanol. Lamellar zinc served as the anode.
The potentials are given relative to a silver chloride
reference electrode placed in a glass vessel with
a saturated aqueous solution of KCl and connected to the
electrolyzer via a Luggin–Haber capillary. Electrolyses
were performed in steady-state and pulsed modes with
an IPC-Pro potentiostat. Rectangular cathodic-potential
pulses were formed with pulse durations τ
of 0.1 to
1.0 s and pauses τ
of 0.5 to 1.0 s. The cathodic deposits
obtained were washed, without being removed from the
electrode, with water and isopropanol, dried in air at
60°C, and examined with REMMA-102-02 and EVO
40XVP scanning electron microscopes.
The effect of the pulsed current in deposition of
dispersed zinc is primarily manifested in distribution
of the deposit over the cathode surface and in the
morphology and conﬁ guration of structural particles of
the deposit. Compared with steady-state electrolysis at
E of –1.7 and –2.0 V (Figs. 1a, 1b, 1g, 1h), the pulsed
current leads to leveling of the dispersed material on the
support (Figs. 1c–1f, 1i–1l). As the duty factor γ (rel.
units, %) decreases,
the tendency toward a uniform distribution of the
deposit over the surface becomes more pronounced. For
example, on passing from γ = 50% (Figs. 1c, 1d, 1i, 1j)
to γ = 20% (Figs. 1e, 1f, 1k, 1l) in an electrolyte with
0.05 M ZnCl
(E = –1.7 and –2.0 V), the size of bushy
formations decreases and the substrate coverage density
by these formations becomes higher.
When a dispersed deposit is formed in a steady-