Investigation of Hydrogen Absorption Kinetics on Intermetallic Compounds Hf2ni, Hf2co and Hf2fe
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Polycrystalline intermetallics Hf2Ni, Hf2Co and Hf2Fe are investigated as the hydrogen absorbers in the temperature range 348 to 823 K, under the constant hydrogen pressure of 1 bar. The absorption process was carried out in typical volumetric apparatus and H/M mole ratios together with rate constants and activation energies for hydrogen absorption reaction were determined. Achieved hydrogen absorption capacities at 573 K are: 0.60, 0.90 and 1.48 and rate constants at 573 K are: 0.38 x 10(-3), 0.55 x 10(-3) and 4.72 x 10(-3) s(-1) for Hf2Ni, Hf2Co and Hf2Fe respectively. Determined activation energies are: for Hf2Ni, 38.44 kJ/mol, for Hf2Co, 19.62 kJ/mol and 2.74 kJ/mol for Hf2Fe. From the obtained experimental results, it was concluded that Hf2Fe has the best hydrogen absorption ability among the examined intermetallics.
Keywords:Hf / Intermetallics / Activation energy / Rate constant / Hydriding capacity / Hydriding isotherm
Source:Hemijska industrija, 2009, 63, 3, 159-162
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