In this work, MgH₂/SiC nanocomposites were fabircated by ball milling Mg powder with SiC nanopowder. By using SiC as an additive, we successfully decreased the grain size of MgH₂, increased the defects, and prevented the agglomeration of MgH₂ crystallites. Results show that small amount of SiC has positive effect on kinetics.
X-ray diffraction (XRD) patterns of the as-prepared samples and the samples after hydriding/dehydriding were obtained. The patterns of as-prepared samples exhibit peaks corresponding to betta- MgH₂ and gama-MgH₂ together with Mg. The results clearly demonstrate that the addition of SiC can help to generate smaller MgH₂ nanocrystals.
The morphology of the nanocomposites was characterized by using scanning electron microscopy (SEM). For all samples, the particles have irregular shapes and agglomerate together, which is a typical morphology of ball-milled powders. However, the uniformity of the particle size is improved for the SiC doped samples, especially for the samples with higher doping level.
Thermal properties of samples were studied using a differential scanning calorimetry (DSC). All the SiC doped samples show a lower onset and a lower desorption temperature than the non-doped sample from DSC traces, and the hydrogen desorption temperature decreases with the SiC content increasing.
The hydrogen absorption behavior of the samples was evaluated by Sieverts method.This behavior is shown in Fig 1. The PCI curves obtained in absorption and desorption mode exhibit a single plateau behaviour for all samples. The hysteresis factor for different samples, defined as ln(Pabsorption/Pdesorption), were calculated.