Abstract: Light weight metal matrix nanocomposites (MMNCs) can be so useful for automobile, aerospace and numerous other applications, but it is extremely difficult to disperse nanosized ceramic particles uniformly in liquid metals. Hence, this paper presents an inexpensive methodfor fabrication of aluminummatrix nanocomposites reinforced with SiO2nano-sized ceramic particles. In this method, ultrasonic technique was used for increasing wettability of reinforcement nanoparticles within the aluminum melt. Microstructure study of aluminum matrix nanocomposites reinforced with different weight percentages of silicon dioxide nanoparticles (0.25, 0.5, 0.75 and 1.0 wt.%) were carried out with an optical microscope and SEM and then hardness of the samples were investigated. SEM observations validateuniform dispersion of nano-sized SiO2 in metal matrix.Hardness of the samples is also significantly increased by addition of SiO2 nanoparticles and Al-SiO2nanocomposite at 0.75 wt.% SiO2 produces the highest hardness.

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