Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 7, pp. 10061009.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © O.A. Mazhaeva, Yu.V. Rublinetskaya, V.V. Slepushkin, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 7, pp. 10741077.
ELECTROCHEMISTRY AND OTHER
PROCESSES OF CHEMICAL TECHNOLOGY
Local Chronopotentiometry of Heterogeneous Alloys
O. A. Mazhaeva, Yu. V. Rublinetskaya, and V. V. Slepushkin
Samara State Technical University, Samara, Russia
e-mail: email@example.com, firstname.lastname@example.org
Received March 27, 2013
Abstract—Abstract-It was shown by the example of zinc-cadmium and lead-antimony alloys that local chrono-
potentiometry is promising method for studying anodic and corrosion properties of heterogeneous alloys.
First, the chronopotentiometric method of the determi-
nation of anodic properties of heterogeneous alloys was
studied by Kazan school electrochemists . Then, the
method was developed by Kolotyrkin et al. [2–4] and by
other authors . The method of local chronopotentiom-
etry (LCP) has not been used yet [6, 7].
The study is devoted to widening the scope of feasibilities
of local electrochemical analysis (LEA), including LCP,
in the study of anodic and corrosion properties of alloys.
Polarization curves for the anodic dissolution of metals
and alloys were recorded on an IPC Pro M potentiostat
in two-electrode clamping cell of special design . The
cell body was made of MPG-9 low porosity graphite with
large and well-developed surface area, which served as a
counter electrode and a vessel for supporting electrolyte
(1 M NaClO
). As working electrode served a minor
surface area (S = 0.0048 cm
) of the metal under a con-
tact hole of an elastic packing of a clamping cell. The
polarization was performed in the galvanostatic mode at
i = 0.6 mA. The dissolution curves of metals and alloys
have clearly resolved plateaus at this polarization current.
Electrochemical dissolution characteristics is transition
time and the quantity of electricity Q, which is easily
determined by substituting the known value of the polar-
ization current into the relation Q = i.
Figure 1 demonstrates chronopotentiograms for pure
metals (zinc, cadmium) and their alloys in 1M NaClO
The zero-current potential of the working electrode, i.e.
zinc and cadmium surface, relative to graphite reference
is –0.95 and –0.60 V, respectively. If the potential of the
graphite electrode (cell body) is constant (+0.20 V relative
to standard hydrogen electrode) [6, 7], then the steady-
state potentials of zinc and cadmium will be –0.75 and
–0.40 V, i.e., close to equilibrium potentials of metals .
In the course of the process, the potential shifts to
positive region owing to increase in concentrations
ions in the vicinity of the electrode
surface. The saturation concentrations of Zn(ClO
in a near-electrode layer cause forma-
tion of a passivation salt ﬁ lm on the electrode surface
and abrupt increase in the circuit potential. The polar-
ization curve for the metal dissolution (Fig. 1) has a
plateau characterized by the following relations :
= —— –——– , (1)
= —— (nFSc
is transition time of dissolution of a pure metal,
, amount of electricity passed during metal dissolu-
tion, D diffusion coefﬁ cient of metal ions, S electrode
concentration of a saturated solution of a metal
salt, and i is polarization current.