Effect of burning temperature on rice husk silica as reinforcement of recycled aluminium chip AA7075

Abstract

Aluminium recycling is now a well-known technique used in material manufacturing because it consumes less energy and is environmentally friendly. This paper presents the effect of burning temperature on rice husk silica as reinforcement of recycled Aluminium chip AA7075 on physical properties and hardness. Rice husk silica was prepared without any chemical treatments which are original rice husk (O), rice husk ash burned at 700°C (RHA) and calcination of rice husk ash burned at 1000°C (CRHA). Recycled Aluminium chip AA7075 reinforced with rice husk silica i.e., 2.5 wt. %, 5 wt. %, 7.5 wt. %, 10 wt. % and 12.5 wt. % were prepared. Analyses of silica were conducted by using x-ray diffraction (XRD) and x-ray fluorescence (XRF) test. Silica remains to be in amorphous phases for original rice husk and rice husk ash at 700°C. However, at a burning temperature of 1000°C, silica was observed in semi crystalline phase. Porosity and water absorption of composite of metal matrix increased with an increasing the composition of rice husk silica. The hardness of composite of metal matrix improved with increasing rice husk silica, while the hardness of chip AA7075/O and chip AA7075/CRHA decreased with increasing rice husk silica. Based on investigation to Aluminium reinforced rice husk at different burning temperatures, amorphous phase of silica burned at 700°C shows good potential to improve the hardness of material by appropriate composition of rice husk silica.