ISSN 1070-4272, Russian Journal of Applied Chemistry, 2016, Vol. 89, No. 8, pp. 1245−1251. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © T.I. Devyatkina, S.I. Luchneva, S.V. Fomicheva, V.V. Rogozhin, G.N. Gavrilov, V.I. Naumov, M.G. Mukhalenko,
2016, published in Zhurnal
Prikladnoi Khimii, 2016, Vol. 89, No. 8, pp. 995−1001.
AND METAL CORROSION PROTECTION
Modiﬁ cation of Nickel-Plating Electrolyte for Deposition
of Coatings onto Aluminum and Its Alloys
T. I. Devyatkina, S. I. Luchneva, S. V. Fomicheva, V. V. Rogozhin*,
G. N. Gavrilov, V. I. Naumov, and M. G. Mukhalenko
Alekseev State Technical University, ul. Minina 24, Nizhny Novgorod, 603950 Russia
Received July 26, 2016
Abstract—Composition of an electrolyte for nickel-plating of anodized surface of aluminum and its alloys was
developed. It is suggested to use ammonium sulfate having rather high buffer properties in acid electrolytes as a
buffer additive. It is suggested to introduce ﬂ uorine-containing substances into the electrolyte in order to obtain
nickel coatings with ﬁ nely crystalline structure and to raise the cathodic current efﬁ ciency. To improve the operation
of the nickel anode and stabilize the cathodic process, it is recommended to introduce into the electrolyte substances
of the pyridine series belonging to the class of imides. The optimal working modes of the electrolyte of this kind
were determined. The electroplated nickel coatings exhibit a high adhesion to the aluminum base without an ad-
ditional thermal treatment, which makes shorter the technological process of deposition of multilayer coatings.
Of particular importance for modern technology are
aluminum and its alloys, which possess such valuable
properties that make them irreplaceable in many cases.
They become even more important when various plated
coatings are formed on their surface and, in particular,
nickel coatings. The attractive outward appearance, high
corrosion resistance, and good mechanical properties
provide the increasingly wide application of nickel for
protective-decorative and functional properties. Coatings
of this kind are used for exterior ﬁ nish of articles and parts
of machines (airbuses, Audi automobiles, and domestic-
made vehicles), apparatus, and electronic devices and as
an intermediate layer for deposition of other coatings.
Owing to its good mechanical properties, nickel is
used for reconditioning of worn parts, galvanoplastic
fabrication of injection molds, etc.
The process in which nickel coatings are deposited
onto an aluminum base is associated with a number of
problems, one of which is the poor adhesion of the coating
to the base. This problem can be solved by preliminary
anodic treatment of the article surface in a mixture of
sulfuric and orthophosphoric acids with addition of
ammonium biﬂ uoride. It has been shown previously 
that a pore-free plated coating with ﬁ nely crystalline
structure can be deposited from acid electrolytes onto an
anodic ﬁ lm formed in this mixture, and this can be done
for any brands of aluminum alloys.
The use of an oxide ﬁ lm as a sublayer introduces a
signiﬁ cant correction into the composition and operation
modes of a nickel-plating electrolyte. For example,
alkaline electrolytes were not considered because of the
chemical instability in these electrolytes of an oxide ﬁ lm
preliminarily formed on the surface of aluminum and its
alloys. Furthermore, high values of the solution pH may
lead to deposition of brittle dark-shade and rough coatings
. Another reason is the high content of depassivating
chloride ions (up to 35–60 g L
) in nickel-plating
electrolytes, which results in that the anodic oxide ﬁ lm
on aluminum is disintegrated in cathodic deposition of
nickel. As a consequence, the adhesion of a coating to
the base is deteriorated. Weakly acid electrolytes with
pH 4.0–4.5 were not considered, either, because nickel
anodes are rapidly passivated in these electrolytes due to
the absence of chloride ions.