ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 2, pp. 264!268. + Pleiades Publishing, Inc., 2006.
Original Russian Text + E. A. Fedorova, E. K. Lysova, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 2, pp. 264!268.
AND CORROSION PROTECTION OF METALS
Chemisorption of Adamantane and Its Derivatives
on the Surface of Anodically Polarized Aluminum
and Titanium Alloys in Anodizing Electrolytes
E. A. Fedorova and E. K. Lysova
State Technical University, Nizhni Novgorod, Russia
Received July 7, 2005
Abstract-The mechanism of action of adamantane compounds added as modifying agents to anodizing
electrolytes was studied. The additives improve the electrically insulating properties of the surface of
aluminum and titanium alloys during anodic treatment.
The theoretical and practical interest in surfactants
whose molecules contain adamantane structures in-
creases owing to their high lipophilicity , thermal
stability , chemical and electrochemical stability
in anodic-treatment processes , and other dis-
tinctive properties . To expand the application areas
of adamantane derivatives, it is of importance to re-
veal the mechanism of their surface activity.
Previously, we have studied the surface activity
and adsorption of adamantane and of a number of its
derivatives on the untreated and anodically polarized
iron, aluminum, and titanium alloys in highly concen-
trated electropolishing electrolytes, in which ions have
virtually no hydration shells [3, 4].
The introduction of adamantane and its derivative,
remantadinum, into low-concentrated anodizing solu-
tions based on sulfuric and oxalic acids (up to 0.6 M)
appeared to be effective in formation of anodic oxide
films (AOF) on aluminum alloys .
According to , chemisorption from aqueous so-
lutions onto metal oxides cannot take place, because,
having a higher affinity for the surface, water mole-
cules hinder adsorption of other compounds. There-
fore, the present study is devoted to analysis of sur-
face phenomena at the alloy3solution and AOF3solu-
tion interfaces in low-concentrated aqueous solutions
for anodizing of aluminum and titanium alloys.
Samples of aluminum (AMts, AMg, and D16) and
titanium (VT10, VT6, and VT16) alloys were sub-
jected to anodic oxidation in an electrolyzer with
a cooling unit and lead cathodes.
Standard anodizing solutions (0.55 M H
0.15 M H
+ 0.075 M Na
) were modified
by addition in an amount of 1.033.0 g l
of the fol-
lowing organic compounds: adamantane (Ad) C
remantadinum (Rem) C
. HCl (1-a-
aminoethyladamantane hydrochloride), and fluorode-
rivatives of adamantane, hexafluoropropyl adaman-
) and perfluoro-1-pro-
penyl adamantanol C
We used for anodic polarization of electrodes a PI-
50-1 potentiostat, LKD-4 X!Y recorder, three-elec-
trode cell, and saturated silver-chloride reference elec-
We studied surface phenomena at the alloy3solu-
tion, solution3air, and AOF3solution interfaces, us-
ing methods for measurement of contact angles with
a Wilhelmi plate [4, 10], boundary tension of solu-
tions after Rebinder , and surface hardness after
Rebinder [3, 9].
We determined the contact angles from the length
l of the chords of a drop profile and drop height h,
both measured with a reading microscope by the pro-
cedure described in , with the drop assumed to
q = 2arctan(2h/l ), (1)
cos q = ÄÄÄÄÄÄÄ .