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 TiH ₂ powder samples. Above the temperature of 750 °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 (∼500 °C).