الفهرس 
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Abstract
Mechanical milling technique has been employed using either mechanochemical , dry milling or wet milling route to prepare aluminum, carbon and silicon carbide nanostructures. In the present work, aluminum nanoparticles have been synthesized via a mechanochemical reaction between sodium metal and aluminum chloride in which the average size of the synthesized nanoparticles was about 30 nm. On the other hand, wet milling of aluminum flake powders was performed for 50 hours in the presence of 1,4 dioxane, 2-ethylhexanol or kerosene under ambient atmosphere to get different sizes of aluminum nanoparticles ranged from 235 to 860 nm with a valuable amount of aluminum oxide. Wet milling was also employed for 50 h in the presence of kerosene under argon to obtain aluminum nanoparticles preserved under kerosene with average size about 50- 80 nm with less amount of aluminum oxide. In the same manner, graphite powders have been milled via the wet milling method in the presence of either kerosene or 2-ethylhexanol as milling solvents. Graphene sheets were successfully exfoliated by this route having few layers with considerable amount of defects. Unlike wet milling, dry milling of graphite was performed to prepare particulated nanocarbon with average size about 50 nm. Mechanochemical reaction between graphite and different sources of silicon such as elemental silicon, fumed silica, powdered glass and white sands was an interesting way to synthesize silicon carbide nanoparticles with different characteristics and different sizes ranged from 20 to 100 nm. Finally, photostability study of the obtained nanostructures was achieved using different light sources such as light emitting diode at different wavelengths (490, 530, and 650 nm), diode laser (401 nm) and sun light. Morphological, structural characteristics and particle size were studied evaluating the changes occurred due to light exposure. It was clearly observed that the morphological, structural characteristics and particle size were not affected upon exposure to light emitting diode whereas valuable changes in aluminum nanoparticles and graphene sheets were detected upon exposure to sun light and diode laser. On the other hand, silicon carbide nanoparticles were not affected upon exposure to the selected light sources. The as synthesized nanomaterials were characterized using XRD, EDX, Raman, FT-IR, TEM and SEM investigations.