Electrochemical Determination of Physicochemical and Mechanical Properties in ZrCr1-xNiMox Hydrides

The formation and decomposition of ZrCr1-xNiMox (x = 0.0, 0.3, 0.6) hydrides were studied in strong alkaline solutions by charge/discharge curves and electrode potential-composition-temperature plots. Dimensionless hysteresis was obtained and related to physicochemical and mechanical magnitudes; yield strengths and hydrogen partial molar volumes. The lowest yield strength (0.88 x 10(7) N cm(-2)) was observed for ZrCr0.7NiMo0.3, which favors hydrogen embrittlement and the increase in the active area. Besides, yield strengths for ZrCr0.4NiMo0.6 are similar to those in the absence of molybdenum. On the other hand, ZrCr0.7NiMo0.3 exhibits similar hydrogen partial molar volumes as in the absence of molybdenum, ca. 33.7 and 34.4 cm(3), respectively. The further rise in molybdenum molar proportions produces an increase in this magnitude, i.e. 48.1 cm(3), due to the different packing density produced by the higher molybdenum atomic radius. Mechanical and electric works are also useful parameters for a hydride design. Therefore, from galvanostatic and zero current chronopotentiometric curves, maximum and lost works were evaluated showing that ZrCr0.7NiMo0.3 offer the largest benefits for storage purposes. From combining electrochemical free energies and discharge currents during the time operating process, the dissipative uncompensated heat was also calculated, showing again that ZrCr0.7NiMo0.3 is the appropriate for hydride applications. (C) 2016 The Electrochemical Society. All rights reserved.