In recent years, hydrogen energy has been extensively used in many fields, hydrogen(deuterium, tritium) storage metals have attracted abroad attention because of their special performance. Titanium, as a kind of hydrogen storage material, had been used in high-vacuum circumstance because of its high hydrogen storage density and extra-high stability of its hydride. On the purpose of developing hydrogen materials and the corresponding alloy films with lower equilibrium pressure of hydrogen desorption, this dissertation is mainly dedicated to study the technique for preparing Ti and Ti-alloy films, and the hydrogen absorption properties of the films.
Ti and Ti-alloy films were prepared by magnetron sputtering. The effect of process parameters, such as substrate temperature, negative bias and depositing time, on the surface morphology, structure and grain size of the films was investigated by XRD and SEM technique. The results indicated that increasing substrate temperature appropriately can improve the film forming abilities, the grain size of the films became larger with the temperature increasing. Ti films deposited at low temperature have (002) preferred orientation, but the preferred orientation was decreased at higher temperature. The addition elements are substitute elements in titanium. Only a small amount Ti2Ni phase was discovered in the alloy films. The addition of Mo caused 他the occurrence of α+β-Ti binary phase. Negative bias can change preferred orientation and decrease the grain size.
Element homogeneity was also investigated. The valence of the surface element was measured by XPS technique. The results indicated that very thin oxide layer formed on the film surface. Segregation of Y in the surface is very strong. The addition of Al can decrease gross segregation of Y. The diffusion layer between the films and the Mo substrate was discovered at high temperature sputtering routine.
The adhesion of the films was tested by stretch method and scratch method. The adhesion increased with substrate temperature and formed a peak at 400℃. At higher temperature, the adhesion decrease. PCT curve at different temperature was obtained and the hydrogen absorption equilibrium pressure at room temperature was extrapolated. The results showed that, the hydrogen absorption properties of the films are lower than that of Ti bulk, additive elements can decrease the width of hydrogen absorption plateau, and raise equilibrium pressure of hydrogen absorption.
Key words: magnetron sputtering, hydrogen storage, titanium, film
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