1070-4272/04/7711-1888C2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 11, 2004, pp. 1888!1890. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11,
2004, pp. 1905!1908.
Original Russian Text Copyright + 2004 by Bespalova, Miroshnichenko, Lovpache, Kudryavtsev.
AND POLYMERIC MATERIALS
Effect of Acidifying Agent on Autophoretic Application
of Polymeric Composite Coatings
Zh. I. Bespalova, L. G. Miroshnichenko, Yu. A. Lovpache, and Yu. D. Kudryavtsev
South Russian State Technical University (former Novocherkassk Polytechnic Institute), Novocherkassk,
Rostov oblast, Russia
Received August 4, 2004
Abstract-The effect of acidifying agent on autophoretic application of a polymeric composite material and
protective properties of the resulting coatings is studied.
Studies concerning intensification of the existing
processes for applying polymeric coatings to metallic
surfaces and improvement of these processes with
regard to environmental problems are directed pri-
marily at searching for novel cost-efficient solutions.
Among such new developments is the autophoretic
method of applying polymeric protective coatings
In this context, combining the unique properties of
Teflon (corrosion resistant, antifriction, and antiadhe-
sive) with the advantages of autophoretic deposition
(no loss of the applied material, possibility of full
automation, uniform thickness of PPC on articles of
complicated geometry, reduced power consumption
owing to utilization of the energy of the chemical
reaction) is a topical scientific and applied problem.
The autophoretic process is realized by immersing
metallic articles in an acidic aqueous composition
containing an organic coating-forming material in the
dispersed form, dispersing and acidifying agents, and
an oxidant [4, 5].
Acidifying agents are introduced to form concen-
tration and electric fields  that arise from a redox
reaction occurring on the metallic surface and cause
motion of the particles in autophoresis . The auto-
phoretic formation of a gel-like PPC is similar to elec-
trochemical corrosion. In the presence of an acidifying
agent, anodic dissolution of a metal (M 6 M
and cathodic reduction of an oxidant or oxygen con-
tained in the system proceed .
Therefore, ionization of a metal takes place only in
the presence of an acidifying agent, being inseparably
linked with autodeposition from acidic solutions. This
process results in oxidation of a metallic support,
which induces the charge and distorts the stability
of the composition.
In this work we developed a composite Teflon-
based material and studied its applicability to auto-
phoretic deposition with regard to the nature of acidi-
PPCs were applied to pretreated surfaces of 08KP
The autophoretic bath was made from Plexiglas.
The process was carried out at 18325oC. A sample
was fixed on a mechanical agitator using a specially
designed holder and immersed in the polymeric coat-
ing-forming dispersion. The rotation rate was 60 rpm.
pH of the composition was measured with a
pH-340 laboratory pH meter. The thickness of PPCs
was determined by the magnetic method using an
MT-2 instrument ; PPC yield, gravimetrically; and
electrokinetic potential of dispersed particles, by the
method of electrophoresis in a parallel-sided cell; and
PPC adhesion to the metallic surface, by the shear
stress according to GOST (State Standard) 14759369.
The tribotechnical characteristics were determined on
an end friction-testing machine. The continuity of
PPCs was measured using an LOK-1M electric-con-
tact defectoscope; the viscosity, with an Ostwald
capillary viscometer; and corrosion resistance, by the
weight loss in corrosive media.
The composition used was found to be stable by
the dry residue, viscosity, aggregation state, and kinet-
ic parameters. Such a stable state was obtained after
optimization of the composition.
As coating-forming agents we used aqueous sus-
pensions of Teflon F-4D and Teflon F-4MD and a
solution of polymethylphenylsiloxane in toluene; as
mineral additives, carbon black, titanium dioxide,
mica, and Aerosil; and as organic solvents, xylene,
butyl Cellosolve, and furfuryl alcohol.