The role of surface coarsening and sintering during thermal decomposition of titanium hydride

Temperature programmed desorption - mass spectrometry was utilized to study the non isothermal hydrogen desorption from as-received and pre-oxidized TiH2 powder samples. Above the temperature of 750 degrees C, hydrogen desorption from the thermally decomposed as received powder is kinetically delayed compared to that from the pre-oxidized samples. The scanning electron microscopy observations suggest that the delay stems from simultaneous surface coarsening and particles sintering that occur predominantly in the as-received powder at lower temperatures. It is also suggested that the difference in morphology evolution of the as-received and pre-oxidized powders originates from the dependence of Ti diffusion on the concentration of oxygen dissolved in Ti, since the oxide layer itself was found to dissociate at lower temperatures (similar to 500 degrees C). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.