Kinetics of hydrogen desorption from titanium hydride under isothermal conditions

Thermal desorption behaviours of titanium hydride powders under isothermal heat treatment conditions were studied using simultaneous thermogravimetry and thermal desorption spectroscopy (TG-TDS) method. The crystal structures and chemical compositions of the heat treated samples were investigated by X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. It was found that the isothermal heating condition was of importance for the ordering of oxygen or surface oxidation. The phase transformation sequences during long time heating were established by combining the changing trends in the temperature/hydrogen content with the TiH phase diagram. A method for evaluating the kinetic parameters for different phase regions was proposed. The activation energies were calculated for these phase regions, and the corresponding rate-limiting steps were suggested.