The effects of microstructural modification by mechanical milling on hydrogen desorption from magnesium hydride

Nanostructured hydrides fabricated by mechanical (ball) milling offer a promising alternative to hydrogen storage in compressed or liquid form. However, ball milling brings about both beneficial and detrimental effects to their hydrogen desorption characteristics. These effects have been studied in the ball milled magnesium hydride, MgH2. A beneficial effect is that the refinement of the hydride powder particle size and the gamma-MgH2 phase residing within the powder particles, acting additively, are responsible for a substantial reduction of hydrogen desorption temperature of MgH2 hydride. A detrimental effect is a reduction of the hydrogen storage capacity after nanostructuring of MgH2 by ball milling. Both effects are presented and discussed. In particular DSC hydrogen desorption curves at the heating rate of 4°C/min of the ABCR powder as received, milled in hydrogen for (a) 0.25 to 5h and (b) 10 and 20h and finally cycled, XRD patterns of MgH2 (Tego Magnan registered trademark) powders milled continuously for 100h, desorption curves under 0.1 MPa H2 at various temperatures of commercial MgH2 powder Tego Magnan registered trademark milled continuously for 20h are presented in the paper.