1070-4272/02/7510-1713 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 10, 2002, pp. 1713!1714. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 10, 2002,
Original Russian Text Copyright + 2002 by Kabanov, Perelygin.
Electrodeposition of Palladium!Zinc Alloy
from Aminoacetic Electrolyte
S. V. Kabanov and Yu. P. Perelygin
Penza State University, Penza, Russia
Received April 4, 2002
Abstract-The influence of the electrolysis conditions and electrolyte composition on the cathodic current
efficiency by the alloy and on the alloy composition was studied for electrodeposition of the palladium3zinc
alloy from an aminoacetic electrolyte.
The industrial use of palladium alloys with nickel,
indium, and some other metals in coatings is due to
lower consumption of the noble metal and enhanced
physicomechanical and chemical properties of the
coatings [1, 2]. The metallurgical palladium3zinc al-
loy is a complex system comprising a solid solution
at zinc content of less than 6% and several chemical
compounds at higher zinc content .
The possibility of obtaining a palladium3zinc alloy
with up to 8% zinc from ammonia3trilonate elec-
trolyte has been shown previously . Since inter-
metallic compounds have enhanced physicomechanical
properties , it is of certain practical and theo-
retical interest to obtain the given alloy with higher
content of zinc.
The alloy was electrodeposited from an amino-
acetic solution in a 100-ml rectangular glass bath with
graphite anodes. The content of zinc in the alloy was
determined by complexometric titration after separat-
ing palladium in the form of palladium dimethyl-
Preliminary experiments showed that quality coat-
ings are formed solely in a saccharin-containing elec-
trolyte. Addition of 0.2531gl
erably decreases (from 10 to 2.5 MPa) the internal
stresses in deposits and increases somewhat (by 13
2%) the content of zinc in a coating.
The influence of the electrolysis conditions and
electrolyte composition on the cathodic current effi-
ciency (CE) by the alloy and on the alloy composition
was studied at 30oC, current density of 0.5 A dm
and pH 7 from a solution containing (g l
chloride 20, zinc chloride 3 (in terms of metal), am-
monium chloride 20, aminoacetic acid 40, and sac-
With increasing zinc concentration c
in an elec-
trolyte, zinc content in a coating, c
, grows and the
cathodic CE by the alloy falls:
0.5 1 2 3
, % 7.7 9 12.8 15.8
CE, % 88.5 84 82 77
The ratio of metal contents in the alloy as a func-
tion of the ratio of concentrations of their ions in
the electrolyte is described by the equation :
log ÄÄÄ = 0.37 + 0.457 log ÄÄÄÄ .
Älog ÄÄÄ = 0.37 + 0.457 log ÄÄÄÄ .
The correlation coefficient of the equation is
R = 0.987.
With zinc concentration in the electrolyte increas-
ing further to 5 g l
, the current efficiency by the
alloy decreases from 77 to 65%, and the content of
zinc in the coating increases to 20%. Lowering the
palladium concentration in the electrolyte under these
conditions results in deterioration of the deposit
When the cathode current density is lowered from
0.25 to 1 A dm
, the CE by the alloy falls from 90.5
to 72% (Fig. 1, curve 1), with the zinc content de-
creasing only slightly (from 15.8 to 17%). At higher
current densities the coating quality deteriorates be-
cause of the cracking resulting from the build-up of
considerable internal stresses.