Electrodeposition and properties of composite coatings based on nickel

Article abstract of DOI:10.1134/S1070427211110309

Composite electrochemical platings based on nickel and containing graphite bisulfate as a dispersed phase were obtained. Their electrodeposition and tribological characteristics were studied and compared with those of electrolytic nickel deposits free from a disperse phase.

Full text of DOI:10.1134/S1070427211110309

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 11, pp. 2005−2007. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.N. Tseluikin, E.A. Vasilenko, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 11, pp. 1920−1922.
BRIEF
COMMUNICATIONS
Electrodeposition and Properties
of Composite Coatings Based on Nickel
V. N. Tseluikin and E. A. Vasilenko
Engels Technological Institute (Branch of Saratov State Technical University), Engels, Russia
Received October 4, 2010
Abstract—Composite electrochemical platings based on nickel and containing graphite bisulfate as a dispersed
phase were obtained. Their electrodeposition and tribological characteristics were studied and compared with
those of electrolytic nickel deposits free from a disperse phase.
DOI: 10.1134/S1070427211110309
Composite electrochemical platings (CEPs) have
received acceptance owing to the fact that they improve
operation properties of metal surfaces (hardness, wear
hardness, and corrosion resistance). Unlike classical elec-
trochemical platings, CEPs are obtained with the use of
electrolytes-suspensions containing dispersion particles
of various sizes and types [1–4].
EXPERIMENTAL
Composite electrochemical platings based on
nickel-graphite bisulfate were precipitated from an elec-
–
1
trolyte of the composition (g l ): NiSO ·7H O, 220;
4
2
NiCl ·6H O, 40; CH COONa, 30; and graphite bisulfate
2
2
3
10. Particle sizes of the disperse phase were up to 10 μm.
The efficiency of CEP application in many respects
is defined by the nature of a dispersed phase. Graphite
and its derivatives are of interest as dispersed materi-
als for composite coatings [4–7]. Graphite has a lay-
ered structure. Interstitial graphite compounds (IGC)
are obtained by penetration of various molecules or
ions in the interlayer space of their crystal lattice
Graphite bisulfate was synthesized by the anodic
oxidation of dispersed powder graphite GSM-1 in the po-
tentiostat regime at room temperature. Dispersed graphite
served as a working electrode, and 12Kh18N10Т steel
was a counter electrode. A 5.32 M solution of H SO4
2
(special-purity grade) served as an electrolyte. Graphite
particles were tightened to a current lead by a sliding pis-
ton, which moved during the interstitial reaction, increas-
ing the volume of a suspension electrode. It allowed us
to hold a constant pressure of tightening graphite during
the whole process.
[
8]. The reaction of graphite with sulfuric acid in the
presence of strong oxidizing agents yields graphite
bisulfate with a composition described by the formula
+
–
C (HSO ) ·2H SO [9].
4
2
4
2
4
There are chemical and electrochemical methods of
Electrodeposition of CEPs was carried out on a
steel base (steel 45) at room temperature with perma-
nent stirring of a solution. Pure nickel was deposited
from the electrolyte of the above composition without
adding graphite bisulfate. Adhesion of the resulting
coatings was estimated by applying a net of scores
the IGC synthesis [10]. The chemical method is techno-
logically simple, but the resulting product is inhomoge-
neous. The electrochemical synthesis allows obtaining
high-purity IGC with a specified composition.
The aim of the present work was to obtain CEPs on
the basis of nickel with graphite bisulfate and to study the
process of their precipitation and tribological properties of
forming coatings. In the work we used graphite bisulfate
synthesized by the electrochemical method.
(
GOST 9.302-79).
Sliding friction coefficient f of electrodeposited coat-
ings was determined according to the scheme given in
[11] and was calculated by the formula
2
005

2006
TSELUIKIN, VASILENKO
tallization centers on the cathode surface, defining the
further growth of the electrolytic deposit.
When nickel coatings are precipitated in the gal-
vanostatic mode, potentials are shifted to the positive
side as graphite bisulfate is added in the nickel-plating
electrolyte (Fig. 2), which confirms the data of potentio-
dynamic experiments. The polarization capacity C was
calculated from the data of galvanostatic measurings by
the expression
where F is force of sliding friction; Р, force correspond-
ing to the pressure which a counterbody put on a test
surface.
fr
A steel sample was used as a counterbody. Its weight
in all experiments was 1 g.
Electrochemical measurements were carried out on
a P-30S pulsing potentiostat. Potentials were set in rela-
tion to the saturated silver-chloride reference electrode
and reduced to the hydrogen scale.
Potentiodynamic polarization curves of nickel pre-
cipitation show that the addition of a dispersed phase
of graphite bisulfate to the nickel-plating electrolyte
facilitates the cathode process (Fig. 1). In the presence of
dispersion particles nickel is precipitated at less negative
potentials. Currents of the CEPelectrodeposition increase
as compared to nickel coatings without a dispersed phase,
which points to an increase in the cathode process rate.
–
2
where i is current density, А cm ; E, potential, V; and
t, time, s.
Values of polarization capacity decrease on passing
from nickel coatings to CEP nickel-graphite bisulfate
see the table). It is attributable to the fact that the size
of a double electrical layer increases when dispersion
particles penetrate in it. Similar changes should affect the
state and properties of the surface of the studied coatings.
(
Transfer of dispersion particles to the cathode can be
carried out not only due to intermixing of the electrolyte,
but also proceed through a stage of adsorption of depos-
ited metal cations on their surface [2]. Having received
such charge, particles are transferred to the cathode and
there are overgrown with uncharged metal. The ions
adsorbed on particles participate in the bridging binding
of a dispersed phase with a cathode surface. This bind-
ing attenuates a disjoining pressure of a liquid interlayer
between a particle and the cathode, thus strengthening
adhesion [12]. Dispersion particles play a role of crys-
The sliding friction coefficient f is one of the most
important characteristics of metal surfaces. Values of f for
nickel-graphite bisulfate CEPtwice decrease compared to
nickel electroplating (see the table). It is connected with
the fact that graphite bisulfate particles penetrating into
coatings on the electrodeposition fulfill a function of a
dry lubrication (the experiment was carried out under dry
friction conditions). Decrease in the friction coefficient
of the studied composite coatings, as compared with pure
nickel, is obviously defined by a layer structure of the
Fig. 2. Galvanostatic curves of nickel precipitation (1) without
Fig. 1. Potentiodynamic polarization curves of nickel precipi-
tation obtained in an electrolyte of nickel-plating (1) without
addition and (2) with addition of graphite bisulfate. (i) current
addition and (2) with addition of graphite bisulfate at i = 4
c
–2
А dm . (Е) potential, V; (t) time, s.
–
2
density, Acm , (Е) potential, V.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 84 No. 11 2011

ELECTRODEPOSITION AND PROPERTIES OF COMPOSITE COATINGS
2007
Polarization capacity and coefficients of sliding friction of
nickel coatings at various cathode current density
on their tribological properties.
REFERENCES
3
–2
С × 10 , Ф cm
f
i, А dm–2
nickel
22.3
CEP
12.8
16.2
22.3
27.8
33.4
38.0
41.8
47.0
52.0
nickel
–
CEP
–
1. Saifullin, R.S., Neorganicheskie kompozitsionnye mate-
rialy (Inorganic Composite Materials), Moscow: Khimiya,
2
3
4
5
6
7
8
9
1
983.
40.1
–
–
2
. Gur’yanov, G.V., Elektroosazhdenie iznosostoikikh kom-
pozitsionnykh pokrytii (Electrodeposition of Attrition-
Resistant Composite Coatings), Kishinev: Shtiintsa, 1985.
52.9
–
–
67.4
–
–
79.7
0.38
0.34
0.34
0.33
0.30
0.16
0.15
0.14
0.14
0.13
3. Antropov, L.I. and Lebedinskii, Ju.N., Kompozitsionnye
elektrokhimicheskie pokrytiya i materialy (Composite
Electrochemical Platings and Materials), Kiev: Tekhnika,
92.8
107.3
119.9
133.2
1
986.
4
. Saifullin, R.S., Fizikokhimiya neorganicheskikh polim-
ernykh i kompozitsionnykh materialov (Physical Chem-
istry of Inorganic Polymeric and Composite Materials),
Moscow: Khimiya, 1990.
1
0
dispersed phase.
5
6
. Vinokurov, E.G., Arsenkin, A.M., Grigorovich, K.V.,
and Bondar’, V.V., Zashch. Met., 2006, vol. 42, no. 3,
pp. 312–316.
Coefficients of sliding friction of composite coatings
nickel-graphite bisulfate also decrease as a coating thick-
–
2
ness increases (i = 10 А dm ):
. Tseluikin, V.N., Solov’eva, N.D., Yakovlev,A.V., and Tse-
luikina, G.V., Perspektiv. Mater., 2009, no. 2, pp. 85–87.
Coating thickness, μm
Friction coefficient
10
0.24
20
0.20
30
0.17
40
0.13
7. Tseluikin, V.N., Fizikokhimiya Poverkhnosti & Zashchita
Materialov, 2009, vol. 45, no. 3, pp. 287–301.
This phenomenon seems to be connected with increas-
ing insertions of dispersion particles in a coating during
its growth in thickness, and also with their more uniform
distribution over the electrodeposit surface.
8. Fialkov, A.S., Uglerod, mezhsloevye soedineniya i kom-
pozity na ikh osnove (Carbon, Interlayer Compounds, and
Composites on its Base), Moscow: Aspect-press, 1997.
9. Ubbelohde,A.R. and Lewis, F.A., Graphite and Its Crystal
Compounds, Oxford, Clarendon Press, 1960.
CONCLUSION
10. Yakovlev, A.V., Zabud’kov, S.L., Finaenov, A.I., and
Yakovleva, E.V., Zh. Prikl. Khim., 2006, vol. 79, no. 11,
pp. 1761–1772.
It has been found that the addition of a dispersed phase
of graphite bisulfate to the nickel-plating electrolyte
facilitates the electrodeposition process and promotes
formation of composite coatings. Penetrating in nickel
electrodeposits, graphite bisulfate renders defining effect
11. Tseluikin, V.N., Solov’eva, N.D., and Gun’kin, I.F., Pers-
pektiv. Mater., 2007, no. 5, pp. 82–84.
12. Saifullin, R.S. and Abdullin, I.A., Ross. Khim. Zh., 1999,
vol. 63, nos. 3–4, pp. 63–67.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 84 No. 11 2011