Increasing hydrogen sorption by ti2ni powder using mechanochemical alloying

Abstract

A method has been developed to increase hydrogen sorption by Ti2Ni powder, which consists in mechanochemical alloying by titanium of Ti-Ni powder near the equiatomic composition. This method allows the hydrogen content in the powder material to be increased several times. It is possible to use the developed powder material for the safe storage and transportation of hydrogen in the metal hydride with a high hydrogen content, with reversible adsorption of hydrogen, in comparison with the storage and transportation of hydrogen in compressed and liquid form. The developed method is simple to implement and low-cost; therefore, it is of economic and practical interest. For mechanochemical alloying, a high-intensity planetary ball mill was used, with a drum rotation speed of 1820 rpm and a processing time of 300 seconds. It is shown that, after mechanochemical alloying, the powder Ti-Ni (85 wt%) – Ti (15 wt%) powder consisted of TiNi in two modifications, namely B2 and B19`, and two Ti2Ni phases with different lattice parameters. The existence of two Ti2Ni phases is due to both the inheritance of this phase from the initial Ti-Ni powder (Ti2Ni(I)), and its formation during the interaction of titanium with TiNi (B2, B19`) in the process of mechanochemical alloying (Ti2Ni(II)). The Ti2Ni (II) phase formed by mechanochemical alloying is more prone to interact with hydrogen with the formation of Ti2NiHx hydride than the Ti2Ni (I) phase present in Ti-Ni powder before alloying. The lattice parameter of the Ti2Ni (II) phase increases by 17.6 % during hydrogenation and corresponds to Ti2NiH2.8 hydride; this result exceeds the change in the cell volume of Ti2Ni obtained by other methods.