Preparation of TiFe based alloys melted by BaZrO3 crucible and its hydrogen storage properties
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Abstract:
TiFe-based hydrogen storage alloy was prepared by using a self-made 25 kg BaZrO3 crucible with ZG-0.05 type vacuum induction melting system. The melting conditions are argon atmosphere of 0.6 MPa, refining time of 5~10 min and temperature of 1 450℃. The chemical composition of the as-cast sample was examined by means of inductive coupled plasma emission spectrometer (ICP) first, and then its microstructure, surface topography, element distribution in micro-domains and phase were examined by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS), and finally its PCT curves were measured by gas reaction controller. The results show that, the oxygen contents of alloys prepared by the BaZrO3 crucible and the graphite crucible are are less than 0.1%(ω), meanwhile the carbon content of alloys obtained by the electro graphite crucible is 0.417%(ω), which exceeds the tolerance of commercial alloys (1 000 ppm). The microstructure of the alloy melted by the BaZrO3 crucible is equiaxed crystal, but the alloy melted by the graphite crucible is composed of the equiaxed crystal and the spherical TiC particles distributed along grain boundaries or within the grain. The maximum amount of hydrogen absorption of the alloy melted by the BaZrO3 crucible is larger than that of the alloy melted by the graphite crucible, and the hydrogen desorption and absorption plateau pressure of the alloy meted by the BaZrO3 crucible is also lower.
