The milling effect during hydrogenation under various conditions for a CaH2-CaB6 mixture was investigated. Two different starting materials, 1) dehydrogenated Ca(BH4)2 and 2) the mixture of commercial CaH2 and CaB6, were used. TG-MS profiles indicated that the hydrogenation kinetics of dehydrogenated Ca(BH4)2 was better than the commercial CaH2-CaB6 especially at high temperature. XRD and IR profiles revealed that Ca(BH4)2 and/or its intermediate state were produced after milling. These results indicate that milling technique accelerates hydrogenation of CaH2-CaB6 even at room temperature, and the initial crystalline size of CaB6 is important to improve the kinetics of the first hydrogenation step.
