Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
2 results
Search Results
Master Thesis Preparation and Characterization of Aluminum Composite Closed-Cell Foams(Izmir Institute of Technology, 2001) Elbir, Semih; Güden, Mustafa; Güden, Mustafa; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAn experimental study has been conducted to investigate the feasibility of the production of SiC-particulate (SiCp) reinforced Al (Aluminum) closed-cell foams using the foaming from powder compacts process and to determine the effect of SiCp addition on the foaming behavior of Al compacts and the mechanical properties of Al foams.The foaming behavior of SiCp/Al composite powder compacts and the compression mechanical behavior of SiCp/Al composite foams were determined and compared with those of pure Al compacts and Al foams prepared by the same processing parameters.Composite and Al powder compacts were prepared by hot uniaxial compaction inside a steel die at 425 oC for 1/2 hour under a constant die pressure of 220 MPa.Compacts of 99 % dense with a small amount of blowing agent of TiH2 (0.5 wt%) were heated above the melting temperature of Al inside a pre-heated furnace. During heating, as the TiH2 decomposed and released hydrogen, the compact expanded uniaxially. Foamed/partially foamed samples were taken from the furnace at the specified furnace holding times and their heights were measured in order to calculate linear expansion.Initial foaming experiments with Al compacts at 750 and 850 oC have shown that foaming at the former temperature was slower and more controllable, although linear expansion was similar at both temperatures. From these experiments, it was also found that rapid cooling of the liquid metal was necessary in order to maintain the liquid foam structure in the solid state.Foaming experiments of SiCp/Al and Al compacts at 750 oC have shown that SiCp addition a) increased linear expansion of the powder compacts and b) reduced the extent of liquid metal drainage. SiCp addition also increased the plateau stress and energy absorption capability of the Al foams. These results have shown the potential of composite foams for tailoring energy absorption of Al foams for varying levels of impact stresses.Foaming experiments have also been conducted on aluminum oxideparticulate/Al and SiC-whisker/Al composites compacts prepared using the same compaction parameters and foamed at the same temperature, 750 oC.Master Thesis Foaming of Waste Glass of a Glass Polishing Factory(Izmir Institute of Technology, 2012) Attila, Yiğit; Taşdemirci, Alper; Taşdemirci, Alper; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe foaming behavior of a glass powder, a residue from a window glass polishing factory in Bursa, was investigated at the temperatures between 700-950°C. As-received glass powder composition, 72.76% SiO2, 11.18% Na2O, 11.31% CaO, 1.74% MgO and 1.61% Al2O3, was well matched with that of soda lime window glass. The expansion of the glass powder compacts started at a characteristic temperature of 690-700 °C and reached a maximum volumetric expansion values at about 866-877 °C. The maximum volume expansion and foam density varied between 700-772% and 0.378-0.206 g/cm3, respectively. The foaming of the compact at 750 °C yielded only crystalline phase of quartz, as the foaming temperature increased over 750 °C, wollastonite and diopsite crystals formed The compressive strength of the foams ranged between 1.9 and 4 MPa and the thermal conductivity between 0.048-0.079 W/K m. Both collapse and plateau stresses increased with increasing relative density, while heating rate was found to be not affect the collapse and plateau stresses. The foamed glass samples showed the mechanical behavior similar to open cell foams. This was attributed to the thicker cell edges and thinner cell walls leading to higher glass material accumulation on the cell edges. The self-foaming behavior of the studied waste glass powder was attributed to the organic compounds within the boron oil which was used as a coolant in the polishing operations.