Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis The Preparation and Characterization of Hydroxyapatite Bioceramic Implant Material(Izmir Institute of Technology, 2000) Çiftçioğlu, Rukiye; Harsa, Hayriye ŞebnemThe use of hydroxyapatite (HA) powders and ceramIcs as a biomaterial was investigated in this work. A commercial HA powder was used for the preparation of HA ceramics and the adsorption of Bovine Serum Albumin (BSA) onto HA has been investigated.The powder and the sintered ceramics were characterized by TGA, DT A, Optical Microscopy, Microhardness Tester, XRD, and FTIR.The sintering studies have shown that it was possible to prepare porous ceramics above 800°C and dense ceramics at 1200-1250°C range.The HA powder lost about 5.5% by weight during heat treatment up to 1000DC and 80% of this weight loss is due to adsorbed water.The particle size of the powder was determined to be submicron whereas the grain sizes of the 1250°C sintered ceramic was in the 1-5 /l um range.A maximum Vickers Hardness of 585 Hv was determined for the 1250°C sintered 97.2% dense ceramic.XRD patterns of the powder and the 1250°C sintered ceramic were identical and almost phase pure. A small CaO peak was detected in the samples which was believed to be remnants of the powder preparation process.The adsorption of BSA onto HA has been studied as a function of time, protein concentration, pH, ionic strength, and HA solids loading. Adsorption experiments were also conducted with commercial alumina and zirconia ceramic powders. Uptake curves have shown that the adsorption process was almost completed in less than ten minutes Adsorption isotherms 'at different pH ( 4.5-7.4) have been obtained and analyzed using the Langmuir model. The Langmuir parameters qm ( maximum amount of protein adsorbed, mg BSA/g HA) and K' (affinity constant, mllmg BSA) have been calculated. qm decreased from 119 to 61.3 with the increase in pH from 4.7 to 7.4. A maximum of 46.1 for K' was determined at pH.5.6 and K' had the lowest value of 3.5 at pH.7.4. Electrostatic attractions were held responsible for the K' maximum at pH.5.6 since HA and BSA surfaces are oppositely charged. The presence of a considerably high amount of BSA adsorption on the HA surface at pH.4.7 where the protein should have close to zero net charge was attributed to hydrophobic effects. The amount of adsorption at equilibrium in the 4.5-5.8 pH range was determined to be twice of that in the 6-8 pH range. Almost 100% of the protein was recovered with a HA solids loading of 750 mg HA/50 ml solution at equilibrium for an initial BSA concentration of I mg BSA/ml solution.Master Thesis Production of Ceramic Tiles by Using Marine Sludge Additives(Izmir Institute of Technology, 2006) Göl, Cem; Çiftçioğlu, MuhsinThe harbour sediment accumulated in time in the zmir Bay was investigated by a number of researchers from various aspects. These sediments called marine sludge in this thesis contain organics and heavy metals which pose an important environmental problem. Marine sludge removed from the harbor is required to be safely kept in some form. In this thesis, production of ceramic tiles by using marine sludge additives was investigated. The sludge is regarded as a suitable raw material for ceramic tile production because of its physical properties and chemical composition. After the sludge is removed from the harbor floor, it was subjected to a series of treatments such as washing, sieving, dewatering, drying and grinding. This treated marine sludge was pressed in the form of pellets and sintered in the 1000-1100 °C range. The treated, untreated and sintered marine sludge along with the separated shells present in marine sludge were characterized by a variety of techniques such as XRD, FTIR, and SEM-EDX. Marine sludge powders at different proportions (0-50 %) were blended via incorporation into a structural ceramic tile raw material. The mixtures were compressed, and then pellets were fired at temperatures in the 1000-1200 °C range with one-hour hold with a firing rate of 10 °C/min. The products were characterized for mechanical and microstructural properties. Marine sludge added tiles were observed to have higher compressive strength after firing at 1100 °C. The sludge addition caused a lower firing temperature for densification/vitrification of the pellets with higher pore content. Their densities and water absorption values were determined. The densities and water absorption of the tiles fired at 1100 °C was observed to decrease with increasing sludge addition. Leaching tests were performed by varying the leach solution pH and ground tile particle size for chemical durability of the products in the final part of the work. The leaching data have shown that heavy metals were immobilized in the vitrified ceramic structure. The results of this work indicated that blending marine sludge in to the ceramic powder mixtures in the 20-50% range was beneficial for tile production.