Magnesium/graphite, mechanical

Table 2.67 Summary of Mechanical Properties of Magnesium-Graphite Composites (5)...

The mechanism of stabilisation of the palladium and magnesium nitrates modifier was not investigated [749]. It is known, however, that palladium nitrate decomposes via the oxide to the metal at 870 °C, which melts at 1552 °C. The appearance temperature for palladium in a graphite furnace is around 1250 °C. As most of the investigated elements are stabilised to temperatures around 1200 °C, it can be assumed that the modifier acts by imbedding the analyte into the palladium matrix, or even by forming a kind of alloy with the analyte. 

H. Imamura, Y. Takesue, T. Akimoto, S. Tabata, Hydrogen-absorbing magnesium composites prepared by mechanical grinding with graphite effects of additives on composite structures and hydiiding properties, J. Alloys Compd. 293-295 (1999) 564-568. 

H. Imamura, S. Tabata, N. Shigetomi, Y. Takesue, Y. Sakata, Composites for hydrogen storage by mechanical grinding of graphite carbon and magnesium, J. Alloys Compd. 330-332 (2002) 579-583. 

Magnesium 99.9%, hydrogen 99.9999%, graphite 99.99% have been used as starting materials. Magnesium powder of weight 1.6-1.8 g has been prepared for the synthesis MgH2 by mechanical size reduction. 

It has been shown that mechanical activation led to substantial increase of specific surface of composites obtained in comparison with initial magnesium hydride and graphite (Table 1). 

Hydrogenation of mechanically treated samples with graphite after the thermal decomposition leaded to the increase of the hydrogen sorption rate in comparison with magnesium produced during thermal decomposition of non-treated MgH2... 

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