ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 2, pp. 170!173. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + D.V. Shilo, E.Yu. Buinitskaya, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 2, pp. 182!185.
AND INDUSTRIAL INORGANIC CHEMISTRY
Effect of the Method of Magnesium Dispersion
on the Process of Hydrogen Absorption by the Metal
D. V. Shilo and E. Yu. Buinitskaya
Mendeleev Russian University of Chemical Engineering, Moscow, Russia
NIIgrafit Research Institute, Moscow, Russia
Received April 27, 2007
Abstract-Absorption of hydrogen by carbon-magnesium composites synthesized by mechanochemical
treatment and arc spraying was studied and methods for optimization of the process of hydrogen absorption
Owing to the high content of hydrogen (7.66 wt %),
magnesium hydride (MgH
) is one of the most pro-
mising materials for accumulation of hydrogen. How-
ever, the high temperature of hydrogen absorption and
release hinders its practical use .
Intermetallic compounds of magnesium, primarily
with nickel and rare-earth metals, obtained by clas-
sical metallurgical methods, exhibit a high rate of
interaction with hydrogen. However, the mass content
of hydrogen in these compounds markedly decreases
because of the increase in their density, caused by
introduction of heavy elements.
An alternative to the conventional metallurgical
methods for improvement of the properties of most of
the hydride-forming metals is their mechanochemical
treatment in high-energy ball mills.
Mechanochemical treatment of a mixture of mag-
nesium and graphite has been used to obtain carbon-
magnesium composites . Composites of this kind
are hydrogenated at lower temperatures (the hydro-
genation temperature decreases by nearly 200oC).
A subsequent analysis of a thermal desorption spec-
trum allowed the authors to record a shift of the hy-
drogen evolution onset to lower temperatures, com-
pared with pure magnesium hydride .
The authors of  obtained carbon-magnesium
composites with nanosize particles by grinding metal-
lic magnesium in liquid hydrocarbons. It was found
that hydrogenation occurs at a higher rate on nanosize
magnesium particles. Already in the first cycle, mag-
nesium absorbs hydrogen at a rate of 6 wt % per hour,
which exceeds by a factor of 1.5 that for magnesium
ground together with graphite to only a micrometer
size (4 wt % per hour). This value is 60 times that for
magnesium with nanosize particles, unmodified with
graphite (0.1 wt % per hour).
Use of graphite instead of heavy elements, com-
bined with mechanochemical treatment, made it pos-
sible to obtain magnesium-based composites that have
lower density and can be hydrogenated (dehydroge-
nated) at lower temperatures.
In , a nickel-magnesium alloy was ground in
a solution of fullerenes in toluene. It was found that
the time of hydrogen desorption from the composite
obtained decreased by a factor of 233, compared with
composites produced by grinding in the presence of
One more method for dispersion of various ma-
terials is, in addition to mechanical grinding, their
evaporation in an electric arc. It is known that this
method of dispersion of carbon materials and, in par-
ticular, graphite can yield carbon nanostructures: ful-
lerenes, nanofibers, and nanotubes. The application of
this technique in the present study yielded a carbon-
magnesium composite in a highly dispersed state.
The goal of the study was to determine how meth-
ods for dispersion of magnesium together with carbon,
namely, joint grinding with graphite and sputtering of
a magnesium-graphite composite in a dc arc, affect
the activation of the carbon-magnesium composites
obtained. The composites were also compared with
the starting magnesium and magnesium ground with-
out carbon additives.