ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 9, pp. 1550!1551. + Pleiades Publishing, Inc., 2006.
Original Russian Text + V.V. Rogozhin, E.Yu. Anan’eva, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 9, pp. 1566 !1567.
Mechanism of Chemical Deposition of Nickel!Boron Coatings
in Tartrate!Glycine Solutions
V. V. Rogozhin and E. Yu. Anan’eva
Nizhni Novgorod State Technical University, Nizhni Novgorod, Russia
Received April 17, 2006
Abstract-The effect of glycine additive on the deposition of nickel3boron coatings from tartrate3glycine
solutions was studied.
Nickel3boron coatings, compared to nickel3phos-
phorus coatings, are more resistant to high tempera-
tures in air, show better barrier properties against dif-
fusion of metal atoms of the substrate, and can be
subjected to high-quality soldering and welding.
At the same time, wide practical application of
borohydride solutions, recommended for chemical
deposition of nickel3boron coatings by GOST (State
Standard) 9308384, is seriously impeded by the pres-
ence of ethylenediamine constituent, which is a
known carcinogen, and by the use of heavy metal salts
as stabilizing additives. The compositions of tartrate3
glycine solutions of chemical nickel plating have been
recommended in .
In this study, we examined how glycine additive
affects the mechanism of the deposition of nickel3
boron coatings from the above solutions. The initial
solution was tartrate3glycine solution  containing
) nickel sulfate 25, K3Na tartrate 50, glycine 50,
sodium hydroxide 80, sodium borohydride 1.0, and
stabilizers. A nickel3boron coating containing about
3.0% boron is deposited from such solution at an
average rate of 739 mm in 30 min.
The electrochemical study was performed in a
standard YaSE-2 cell using PI-50 and P-5848 poten-
tiostats. The coating thickness was calculated from the
gain in the coating weight per visible surface of the
electrode. Mercury oxide electrode was used as refer-
ence. The potentials were recalculated relative to
standard hydrogen electrode. The experiments were
performed at 85oC for 30 min.
The electrochemical mechanism of the chemical
deposition of nickel3boron alloy from tartrate3glycine
solution was confirmed by the dependence of the
nickel plating rate on the potential, which passes
through a maximum (Fig. 1). The deposition rate is
maximal in the vicinity of the compromise potential
of chemical nickel plating, when the steps of cathodic
deposition of the coating and anodic oxidation of the
reductant are kinetically compensated. These steps are
actually interrelated: the shift of the electrode poten-
tial to the negative direction from the compromise
potential of the chemical nickel plating considerably
decreases the rate of the coating deposition. Accelera-
tion of the external electroplating of the coating is far
from compensating the decrease in the rate of the
Evidently, this fact indicates that the adsorbed
reductant, borohydride, whose reactivity in the region
of electronegative potentials is decreased, exhibits the
Fig. 1. Coating thickness d in nickel deposition from initial
solution vs. potential E.(1) Total curve; partial curves: (2) ex-
ternal electroplating and (3) chemical deposition.