Atomic layer deposition of alumina on γ-Al2O3 nanofibres

Atomic layer deposition (ALD) has been exploited for coating -alumina nanofibres with amorphous alumina, using trimethylaluminium Al(CH3)(3) (TMA) and water as precursors. The experiments were carried out at 150 or 300 degrees C, using 100 cycles (or an integer multiple of it) of ALD treatment. Heat-treatment was applied to the fibres to evaluate possible changes in ALD process development. Some samples were compacted and hardness was measured to preliminarily evaluate the effect of ALD and possible usage of fibres as raw material for hard ceramics. X-ray absorption spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and Vickers hardness test were used to characterize the fibres (with and without ALD coating). Alumina nanofibres can be considered as reinforcements in structural composites or as a material for inorganic membranes, suitable to applications at elevated temperatures.