Simulation studies and safety analysis of high pressure milling vials for the direct synthesis of high capacity metal hydrides

• High pressure milling vials have been designed for application in common planetary milling apparatus.
• The load applied at 120 bar inner pressure is simulated to be only one third of the sustainable load capacity of the vials.
• Direct synthesis of high capacity hydrides such as, MgH2, KAlH4 and NaAlH4 was obtained by milling at elevated pressures.
• The performance of high pressure mechanosynthesised materials exceeds that of commercially available samples.

The present study reports the design and safety analysis of high pressure mechanical milling vials designed for the direct synthesis of high capacity metal hydrides. The theoretical calculations and the simulation studies reveal that the load applied at 120 bar inner pressure is only one third of the sustainable load capacity of the milling vials. The advantages offered by direct synthesis of high capacity hydrides such as, MgH2, KAlH4 and NaAlH4 at high pressures were demonstrated by ball milling the reactants Mg + 0.03C, NaH + Al + 0.03TiF3, KH + Al + 0.03TiF3 at the hydrogen pressures, respectively, 30, 60 and 100 bar in the designed vials.