EFFECT OF SiC ADDITION ON HYDROGEN DESORPTION PROPERTIES OF NANOCRYSTALLINE MgH۲ SYNTESIZED BY MECHANICAL ALLOYING

In this study, the composite material with composition of MgH۲-۵ wt% SiC has been prepared by co-milling of MgH۲ with SiC powder. The effect of milling time and additive on MgH۲ structure, i.e. crystallite size, lattice strain, particle size and specific surface area, and also hydrogen desorption properties of obtained composite was evaluated by thermal analyzer method and compared with pure un-milled MgH۲. The phase constituents and grain size of powder were characterized by X-ray diffractometry method. It has been shown that addition of ۵ wt% SiC to MgH۲ and mechanical alloying up to ۳۰ h formed a nanocrystalline composite with the average crystallite size of ۱۲ nm, average particle size of ۰.۵ µm and specific surface area of ۱۰ m۲/g. On the other hand, SiC can help to break up particles and reduce the particle size. As a consequence, the desorption temperature of composite material milled for ۳۰ h has decreased from ۴۳۵ °C to ۳۶۱ °C.

Keywords:

Magnesium hydride , Mechanical alloying , Hydrogen desorption temperature , SiC addition