FABRICATION OF ALUMINUM MATRIX COMPOSITES REINFORCED WITH Al2ZrO5 NANOPARTICLES SYNTHESIZED BY SOL-GEL AUTOCOMBUSTION METHOD

摘要

Nano-crystalline Al2ZrO5 with particle size of about 38 nm was directly synthesized by combination of sol-gel auto-combustion and ultrasonic irradiation techniques from metal nitrates and glycine as fuel. The overall process involves three steps: formation of homogeneous sol at 50?C; formation of dried gel at 110?C, and combustion process of the dried gel at 400?C. The auto-combustion was considered as a heat-induced exothermic oxidation-reduction reaction between nitrate ions and carboxyl group. After autocombustion, product was calcined at 1100?C and was placed in ultrasonic bath for 15 min at room temperature. Aluminum alloy matrix composites reinforced with 0.75, 1.5 and 2.5 vol. % Al2ZrO5 nanoparticles were fabricated via stir casting method. Fabrication was performed at various casting temperatures, viz. 800 and 850 °C. The resulting composites were tested for their nanostructure and present phases by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Based on the obtained results, optimum amount of reinforcement and casting temperature were determined by evaluating the density, hardness and compression tests of the composites. Consequently, experiments illustrated that distribution of nano Al2ZrO5 particles in aluminum matrix is suitable. Also, reinforcing the Al matrix alloy with Al2ZrO5 nanoparticles, improved the hardness and compressive strength of the alloy to a maximum value of 61 BHN and 900 MPa, respectively. The most improved mechanical properties were obtained with the specimen including 1.5 vol. % of Al2ZrO5 produced at 850°C.