The influence of mechanical milling parameters on hydrogen desorption from Mgh2-Wo3 composites

The influence of different milling conditions obtained using two high-energy mills on hydrogen desorption from MgH2-WO3 composites was investigated. The morphology, particle and crystallite size were studied as a function of milling speed, vial's volume, and ball-to-powder ratio. The vial's fill level, the number, and type of milling balls and additive's content kept constant. Changes in morphology and microstructure were correlated to desorption properties of materials. Higher milling speed reduced particle size but, there is no significant crystallite size reduction. On the other hand, additive distribution is similar regardless of the energy input. It has been noticed that different energy input on milling blend, which is the result of combined effects of above-mentioned factors, reflects on desorption temperature but not on the kinetics of desorption. In fact, desorption mechanism changes from 2D to 3D growth with constant nucleation rate, despite obtained changes in microstructure or chemical composition of the material.