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Improved ball milling method for the synthesis of nanocrystalline TiFe compound ready to absorb hydrogen

2019; Elsevier BV; Volume: 45; Issue: 3 Linguagem: Inglês

10.1016/j.ijhydene.2019.11.035

1879-3487

L.E.R. Vega, Daniel Rodrigo Leiva, Ricardo Mendes Leal Neto, Wágner Batista Silva, Rafael Silva, Tomaz Toshimi Ishikawa, Cláudio Shyinti Kiminami, Walter José Botta Filho,

Nanomaterials for catalytic reactions

In this study, we propose a method to produce nanocrystalline TiFe powder by high-energy ball milling, in order to avoid the common sticking problem of the material to the milling tools, assuring a material prompt to absorb hydrogen as well. The method consists of making a preliminary milling operation with the elemental powders (50:50 stoichiometric ratio) to form a strong adhered layer of the milled material on the surfaces of the vial and balls. The main milling operation is then performed with a new powder charge (same composition as before), but now adding a process control agent (stearic acid). Various processing times - 2, 6, 10 and 20 h - were used in the milling experiments. Nanocrystalline TiFe was synthesized in this way with low oxygen contamination, full yields for milling times of 6 h or over, requiring no heat treatments for the first hydrogen absorption. Hydrogen storage capacity of 1.0 wt% at room temperature under 20 bar was attained by the sample milled for 6 h. Kinetic data from samples milled for 2 h and 6 h agreed with Jander model for the rate limiting step of the hydriding reaction, which is based on diffusion with constant interface area.