Effect of rice husk silica reinforcement on recycled aa7075 aluminum chip matrix composite properties

• Main Author: Mohd Joharudin, Nurul Farahin
• Format: Thesis
• Language: English; English; English
• Published: 2020
• Subjects: TA401-492 Materials of engineering and construction. Mechanics of materials
• Online Access: http://eprints.uthm.edu.my/401/1/24p%20NURUL%20FARAHIN%20MOHD%20JOHARUDIN.pdf; http://eprints.uthm.edu.my/401/2/NURUL%20FARAHIN%20MOHD%20JOHARUDIN%20COPYRIGHT%20DECLARATION.pdf; http://eprints.uthm.edu.my/401/3/NURUL%20FARAHIN%20MOHD%20JOHARUDIN%20WATERMARK.pdf; http://eprints.uthm.edu.my/401/

Nowadays, solid waste problem has becomes one of the most popular issues. Due to these problems, recycling becomes more competitive to prevent the shortage of significant aluminum resources while reducing the cost of operating. This research was carried out based on the recycling of aluminum alloy AA7075 reinforced silica by rice husk (waste natural fibers) as metal matrix composite. This study approaches the solid state technique to investigate the effect of rice husk silica as a reinforcement agent in metal matrix composites as it has remarkably lower operation cost and energies compared to conventional recycling by casting. Recycled aluminum chip AA7075 with addition of composition (2.5,5,7.5,10 and 12.5)wt%, of untreated and treated rice husk silica using hydrochloric acid to fasten burning process at different temperature (as-received, 700 and 1000)°C, were prepared by using cold compaction method. The setting of load compaction is 9 tons for 20 minutes and then sintered at temperature of 552°C. The properties of metal matrix composites consisting of physical tests (density, porosity and water absorption), mechanical properties (hardness and compression test) and morphology analysis (optical microstructure and scanning electron microscopy) were investigated. For physical properties, the results show that when the density of metal matrix composite is low, the percentage of porosity and water absorption increases. For mechanical properties, the hardness of metal matrix composite were increased up to 10 wt% of rice husk silica which was 65.93 Hv for untreated, and 69.52 Hv for treated rice husk compared to aluminum chip sample with 53.49 Hv. For the compressive strength, the composition of rice husk silica at 5 wt% gave high strength with 333.63 MPa for untreated, and 322.52 MPa for treated rice husk silica compared to aluminum chip sample with 290.47 MPa.