High strength to weight ratio of aluminium reinforced as metal matrix composites is a well known material used in automotive application. The effects of recycled aluminium chips AA7075 with amorphous silica by rice husk ash on the physical properties and microstructure were investigated. Recycled aluminium chip AA7075 was reinforced with agro waste of amorphous silica rice husk ash i. e., 2.5 %, 5 %, 7.5 %, 10 % and 12.5 %. Samples of these metal matrix composites were prepared by cold compaction method due to the lower energies consumption and operating cost compared to conventional recycling by casting. Physical testing of density, apparent porosity, water absorption and hardness tests of the metal matrix composites samples were examined in the current study. The density of metal matrix composites was increased up to 5 % of amorphous silica, and then decreased with increasing mass fraction of amorphous silica. Porosity and water absorption of metal matrix composites were significantly consistent at increasing mass fraction of amorphous silica, while the hardness of metal matrix composites was increased at increasing amorphous silica. Consequently, the microstructures of metal matrix composites were observed via optical microscope to analyze the dispersion of the reinforced composites. The microstructures of metal matrix composites were found non‐homogeneous and random distribution of amorphous silica and aluminium chip AA7075 compared to 100 % recycled aluminium chip AA7075. Based on investigation to aluminium reinforced rice husk ash composites, it has good potential to improve the material behavior of metal matrix composites by appropriate composition amorphous silica to composite.
Efficient electrical energy usage has been recognised as one of the significant factors to reduce the cost of electrical energy consumption. In this world, hospitals are public buildings that use the enormous energy of other buildings. Due to its 24 hours service, the use of hospital building energy is estimated to be among the highest compared to commercial and residential buildings. In this research, the main building of Putrajaya Hospital has been selected. The main building covered by the first floor until the fifth floor will be focused to conduct this research. This research aims to identify energy consumption, cost savings and the provision of solutions to achieve the cost savings target of Putrajaya Hospital. The characteristics and location of the building were recognised at the beginning of the research. Besides, this study was continued by identifying the lighting system presented at Putrajaya Hospital and the electricity tariff published by Tenaga Nasional Bhd. The calculation of energy consumption and cost for each floor of the main building, starting from the first floor to the fifth floor proposed the energy saving method. Four potential savings methods are proposed later in this research which include the switch to LED lighting saving potential, occupancy sensor, regular maintenance, and reduce light operation hour by using the alternate system. The result was found that energy consumption can be reduced up to 73.38% by switching the current lamp to LED lamp.
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.
Solid state recycling aluminium AA6061 chips by cold compaction is a technique that used lower energy consumption and operating cost compared to the conventional recycling technique by casting. This research is to investigate physical characteristics of the milled recycling aluminium AA6061 according to the change of the time (heat treatment) using the high speed milling process and followed by a cold press forging process. Physical property of the recycled aluminium chip of AA6061 were studied. On the other hand, the results were showing that the porosity and density, and compression is correlated. At 8 hours on variable of quenching have a best value porosity (1.95%), density (2.55 g/cm3) and compression strength (315.19 MPa). While for the variable of aging, the best value of density (2.54 g/cm3) and compression strength (280.76 MPa) is at 10 hours. On porosity the best value is at 8 hours (2.79 %). It must be considered to the density and compression strength. For that, 10 hours were chosen for the best aging time. It can be concluded; the best quenching time is 8 hours and aging time is 10 hours.
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