"THE FORMATION OF HYDRIDES IN Pd-Ni ALLOYS"
The main aim of this work was the distinction between thermodynamical and kinetical reasons of penetration depth limitation of nickel hydride. The investigations have been performed for Ni0.9Pd0.1, Ni0.7Pd0.3, Ni0.5Pd0.5 and Ni0.3Pd0.7, alloys, hydrogenated by high pressure gaseous hydrogen. Wire samples of different radii were hydrogenated under the same conditions, that means under the same pressure, temperature and time.
It has been obtained, that the penetration depths of hydride phase are linear functions of wire radii. Thus, there are two coexisting phases in each alloy: the external hydride phase and the unpenetrated metal. Because the experimental time was much longer than the time needed for diffusion, the results obtained speak for the thermodynamical reason of penetration depth limitation.
Further the formation and desorption pressures, as well as the calculations of free energies and excess free energies of formation are presented.
The thermodynamic potential of hydride formation, taken as a function of nickel content exhibits large changes in alloys reach in palladium and small changes in alloys, in which nickel prevails.
Such a result (which is a consequence of large differences, between formation pressures in palladium and nickel) speaks for the dominant role of nickel in thermodynamical properties of
- B. Baranowski, L. Dębowska: "Free Energy of Hydride Formation in Pd-Ni Alloys System"; Polish J. Chem., 77, 1207 (2003).
- B. Baranowski, L. Dębowska: "The Nature of Phase Transitions in Me-H Systems. Coherent and Incoherent Equilibria"; Polish J. Chem., 77, 1213 (2003).
- B. Baranowski, L. Dębowska: "Limited Penetration Depths of Hydrides in Cylindrical Pd-Ni Alloys Samples"; Polish J. Chem., 79, 783 (2005).