Hydrogen storage properties of as-synthesized and severely deformed magnesium - multiwall carbon nanotubes composite
We prepared a Mg-2 mass % multiwall carbon nanotubes composite employing a powder metallurgy technique. The kinetics of hydrogen absorption/desorption of the as-synthesized composite was much faster than that of reference samples of pure Mg. The pressure-composition isotherm (measured at 300 degrees C) of the as-synthesized composite exhibited no measurable pressure hysteresis, with the equilibrium hydrogen pressures in the plateau region being higher than those of pure Mg by a factor of up to 1.8. Equal channel angular pressing of the as-synthesized composite led to a slow down of the absorption/desorption processes at the initial stages of the processes, and to their acceleration at the later stages. We suggested that the mechanism responsible for the good kinetic performance of the as-synthesized composite was fast diffusion of hydrogen through the cores of carbon nanotubes. We put forward a hypothesis relating the increase in equilibrium hydrogen pressure in the as-synthesized composite to the elastic constraints imposed by carbon nanotubes on the Mg matrix. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
Keywords: Equal-channel angular pressing (ECAP) ; Magnesium alloy ; Carbon nanotubes ; Hydrogen storage properties ; Moderate Temperatures ; Adsorption ; Microstructure ; Deformation ; Graphite ; Hydride ; Alloy ; Mgh2
Record created on 2011-12-16, modified on 2016-08-09