1070-4272/02/7508-1234 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 8, 2002, pp. 1234!1236. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 8, 2002,
Original Russian Text Copyright + 2002 by Medvedev, Makrushin.
AND CORROSION PROTECTION OF METALS
A Study of the Kinetics of Tin Electrodeposition from Sulfate
Electrolyte with Organic Additives
G. I. Medvedev and N. A. Makrushin
Novomoskovsk Institute, Mendeleev Russian University of Chemical Technology, Novomoskovsk, Tula oblast, Russia
Received January 15, 2002
Abstract-The method of Faraday impedance was applied to study the kinetics of tin electrodeposition from
a sulfate electrolyte in the simultaneous presence of syntanol DS-10, formalin (37% solution), and benzyl
Previously, the kinetics of tin electrodeposition
from a sulfate electrolyte in the presence of syntanol
DS-10 has been studied . Dull tin coatings have
been obtained in this electrolyte. It has been shown
that the kinetics of tin electrodeposition depends on
the electrode potential and is gaverned by a hetero-
geneous and a homogeneous chemical reactions.
In , the electrodeposition of tin from a sulfate
electrolyte in the presence of syntanol, formalin (37%
solution), and benzyl alcohol was studied. It was
shown that that, with these organic substances present
simultaneously in an electrolyte subjected to stirring,
shining coatings are formed at i
=4312 A dm
It was of interest to study the kinetics of tin electro-
deposition in the presence of these organic substances.
This was done, as in , using the Faraday impedance
method. The differential capacitance was measured
during electrolysis with an R-5021 ac bridge at fre-
quencies in the range 200 Hz320 kHz on an electrode
made of tin-coated platinum wire (S = 0.126 cm
placed at the center of a platinum-black-coated plat-
inum cylinder. Electrochemical measurements were
carried out using a P-5878 potentiostat in an electro-
lyte stirred with a magnetic stirrer.
A tin layer 10 mm thick was deposited onto the sur-
face of the working electrode. The electrode surface
was refreshed before making a measurement at each
potential. The discrepancy between the results of
measurements in different series did not exceed 5%.
The potentials are given relative to a standard hydro-
gen electrode. The differential capacitances in electro-
lytes with organic additives are given with account of
the roughness factor f. The procedure for determining
f was described in .
The results obtained in measurements of the dif-
ferential capacitance C at different electrode potentials
show that C decreases with increasing frequency and
is constant in the range 30350 kHz. It was assumed
on the basis of this fact that the differential capaci-
tance measured at these frequencies is the capacitance
of the electrical double layer (EDL).
The measurements were done using a series equiv-
alent circuit. The C
values obtained with
an ac bridge were recalculated to C
. The equivalence of the circuit was verified using
the procedure described in . The electrode imped-
ance components R
and 1/w C
were studied in rela-
tion to w
The results obtained in measuring the cathode cur-
rent density and EDL capacitance as functions of the
electrode potential demonstrate that organic additives
inhibit tin electrodeposition (Fig. 1, curves 1 and 2).
At potentials in the range 30.3_30.4 V the EDL
Fig. 1. (1) Cathode current density i
and (2) differential
capacitance of the electrical double layer, C, at 30 kHz vs.
the electrode potential E. Electrolyte composition (g l
100, syntanol 2; formalin and benzyl
alcohol 6 ml l
each; mechanical stirring.