الفهرس 
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Abstract
Cost-effectiveness and environmentally friendly nature of green synthesis methods of nanoparticles are considered the primary motivations that attract researcher’s attention nowadays. Conventional physical and chemical synthesis methods have one major drawback compared to the eco-green method produced in this work; it is the long reaction time. In this research, several techniques for preparing silver nanoparticles (AgNPs) are introduced and utilized to reiforce the Al6061 alloy matrix.
This thesis investigates the improvement in mechanical properties of reinforced Al6061 and compares it to the un-reinforced composite using powder metallurgical (PM) routs. It utilizes the nanoparticles strengthening approach to optimize certain mechanical characterestics of the prepared samples, which were sintered at two different temperatures (550˚ C, and 600˚ C) for optimization purposes. Al6061 powder was used as the Aluminum Matrix Composition (AMC) and silver nanoparticles (AgNPs) were used as the reinforcement material.
Three methods were used for AgNPs production,.The first method involved exposing a mixture of Aloe-Vera leaf extract and Silver Nitrates (AVE1-AgNO3) to microwave irradiation. The second method used ethanol instead of water to prepare AVE2 then exposing the mixture (AVE2- AgNO3) to microwave irradiation. The third method involved using AVE2 without microwaves. The prepared nanoparticles were characterized by XRD analysis before implementation. AMC and AgNPs were weighted and mixed according to the literature’s recommendation at four mixing ratios namely 0 wt.%, 0.5 wt.%, 1 wt.%, and 2 wt.%. The mixtures were compacted by a cold press forming green compact samples that were divided into two main groups and sintered at 550˚ C and 600˚ C. Each group was composed of 8 samples, with two samples for each mixing ratio. The produced samples’ were cylindrical with a diameter of 10 mm and height of 10 mm. Samples were examined in terms of density, hardness, compression strength, friction coefficient, and wear rates. Additionally, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, mapping analysis, and XRD were used to investigate the microstructural behavior.
XRD analysis clearly identified the formation of AgNPs in the three introduced methods and showed variations in average particle sizes and powder morphology. For AMC samples, the highest hardness values were recorded in the 2 wt.% AgNPs reinforced composite that was sintered at 600˚C. The lowest value was obtained for the un-reinforced sample sintered at 550˚C. Furthermore, the highest compression strength was recorded for 2 wt.% AgNPs reinforced composite sample sintered at 600˚ C. For further evidence, wear rate and friction coefficients were investigated. The friction coefficient was calculated, while wear rates were measured. The relation between weight loss rates and AgNPs’ content was investigated and showed enhanced behavior. It recorded improvement of 82% for addition of 1 %wt. AgNPs in wear resistance. Such enhanced composite characteristics might have critical applications in some medical and aerospace fields as it has been proven that AgNPs have improved anti-bacterial resistance, which should contribute to industrial-medical development.