Hydrogenation of passivated aluminum with hydrogen fluid

Hydrogenation conditions of passivated aluminum were examined in a pressure and temperature range of 6-10 GPa and 300-800 degrees C, respectively. The relationship between the hydrogenation reaction yields and holding time was analyzed by Johnson-Mehl-Avrami equation. An Avrami exponent n of 0.3 indicated that the reaction decreased with time due to the low diffusivity of hydrogen in AlH3. The oxide layer on passivated aluminum seemed to be partly removed or modified by pressure-temperature treatment above 6 GPa and 600 degrees C in hydrogen fluid. The hydrogenation pressure of 9 GPa for the passivated aluminum was reduced to 6 GPa.