In order to heighten the nickel content in mesoporous silica frameworks, a new direct synthesis method, called modified DS method, has been developed instead of the commonly used direct synthesis method. In addition, with the aim of incorporating a high amount of titania into SBA-15 mesoporous silica without blocking its mesopores, a multistep impregnation method, called the MSI method, has also been developed. By using the two developed methods, high nickel- and high titania-containing mesoporous silicas obtained werc synthesized. The nickel- and titania-containing mesoporous silicas were characterised by various techniques, i.e. XRD, TEM, EDX, SENI, N2-sorption, XPS, FTIR, UV-Vis-DRS, UV-VIS, TPR, and Raman spectroscopy. For nickel-containing mesoporous silicas synthesized by the modified DS method, satisfactory mesostructures were obtained and the nickel content was increased up to 14.7 wt.%. So far, no reports have been published on synthesis of mesoporous MCM-41-type silica with higher nickel content than 3.6 wt.% using DS method. Via our modified IDS method, high BET surface area (>840 rný/g) and pore volume (>-0.73 cm3/g were also achieved. Nickel was found to be incorporated into the silica frameworks. Formation of nickel phyllosilicates was also confirmed. After activation, mesostructurcs were still intact. Small nickel clusters embedded in the silica walls were found. A high amount of titania (up to 24.4 wt.%) was incorporated into the mesoporous SBA-15 silica via the multistep impregnation method. No damage to the SBA-15 silica mesostructures was caused. The existence of small titania nano-domins was confirmed to be present by Raman and UV-vis-DRS measurements. High dispersion of them was realized via this method according to the results of low-anglc XRD, TEM and N2-sorption measurements. Importantly, no blockage of mesopores was observed. Photo-activity tests showed the superiority of the materials synthesized by the MSI method to those by one-step impregnation method.

In this study a variety of surface modifiers were absorbed onto titania pigment and their interaction examined. / Thesis (PhDAppliedScience)--University of South Australia, 2006.

The aim of the research presented in this thesis was to increase the understanding of the interaction between polymeric dispersants and titania pigment particles. In particular, the effects of dispersants of varied functionalities on the pigment dispersion behaviour in both aqueous suspension and dry paint film were investigated. / Thesis (PhDEng(MineralsandMaterials))--University of South Australia, 2004.

Hydrophobic colloidal suspensions are common in nature and industry. DLVO theory has been used to model the interactions between colloidal particles for decades, however the origin of long-ranged attractive forces observed between hydrophobic colloids remains the subject of much debate. In an effort to understand these forces and improve the prediction of colloidal stability, the colloidal stability of synthetic silica and titania was studied at various concentrations of dissolved gas, KCl electrolyte and pH. / Thesis (PhD)--University of South Australia, 2003

Hydrophobic colloidal suspensions are common in nature and industry. DLVO theory has been used to model the interactions between colloidal particles for decades, however the origin of long-ranged attractive forces observed between hydrophobic colloids remains the subject of much debate. In an effort to understand these forces and improve the prediction of colloidal stability, the colloidal stability of synthetic silica and titania was studied at various concentrations of dissolved gas, KCl electrolyte and pH. / Thesis (PhD)--University of South Australia, 2003

Titania slag is a feedstock to the pigment industry, which in turn provides titania pigment to producers of everyday products like paper, cosmetics and toothpaste. Titania slag is the primary product of the pyrometallurgical process of ilmenite smelting – the other products being iron and CO gas. Titania slag is typically tapped from the furnace into blocks of approximately 20 tons. After cooling these blocks are crushed and milled to size fractions suitable for the processes of the pigment producers. These processes are broadly grouped into two types of technology: the chloride route (during which titania slag is reacted with chlorine and subsequently re oxidised thereby removing the impurities) and the sulphate route (in this process the titania slag is purified after dissolving the slag in sulphuric acid). Due to the nature of these two processes, several specifications are imposed on the quality of the titania slags. The fluidised-bed technology used in the chloride process limits the size distribution of the slag to between 106 µm and 850 µm. Ilmenite smelting industries consequently crush and mill the titania slag to below 850 µm. The fraction below 106 µm is then sold to the sulphate market. Since the coarser chloride grade product is the more valuable product, slag producers continuously strive to improve the ratio between the coarser and finer fractions. This study reports on parameters which influence the particle size distribution of titania slags and therefore the split between the coarser (more valuable) and finer (less valuable) products. Pilot-scale slag ingots were used to identify chemical and process variables which influence the yield of coarser material. The microstructure of as-cast and milled slag was examined, and indicated a role of silicate phases in the crushing behaviour. Industrial-scale slag ingots were used to test whether the roles of tapping rate and water cooling (as identified from the pilot-scale ingots) also applied under industrial conditions. A numerical method was applied to estimate the thermal conductivity of the solidified slag (from measurements on pilot-scale ingots), and to predict the cooling and solidification behaviour of industrial-scale ingots. The study concludes that the chemical composition and cooling conditions of the slag block play central roles in the final particle size distribution of the slag. / Thesis (PhD (Metallurgical Engineering))--University of Pretoria, 2009. / Materials Science and Metallurgical Engineering / unrestricted

京都大学 / 0048 / 新制・論文博士 / 博士(工学) / 乙第12770号 / 論工博第4096号 / 新制||工||1577(附属図書館) / 30663 / (主査)教授 田中 庸裕, 教授 安部 武志, 教授 阿部 竜 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Nanocrystalline hydroxyapatite (HAp) powder of size 10-20 nm was synthesized applying microwave radiation using calcium nitrate tetrahydrate and sodium phosphate dibasic anhydrous as the starting materials. Microwave power of 600 W and Ca/P ratio of 1.66 in the starting chemicals served as the major factors in the synthesis of nanocrystalline HAp powder. Phase composition and evolution were studied using X-ray diffraction (XRD) technique. Morphology, agglomeration and particle-size of the synthesized powder were studied using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Energy Dispersive Spectrum (EDS) was used to determine the elemental composition of the powder. Thermal properties were investigated using Thermogravimetric (TG) and Differential Thermal Analysis (DTA) and, Fourier Transform Infrared Spectroscopy (FTIR). As-synthesized HAP and TiO2 powder was uniaxially compacted into cylindrical pellets at a pressure of 78.69 MPa and sintered at high temperature to examine the effects of sintering on nano powder particles, densification behavior, phase evolution and mechanical properties. Phase evolution was studied using XRD whereas microstructure evolution was studied by SEM. To determine the mechanical properties Vickers hardness and biaxial flexural strength tests were performed. Biodegradability and biomechanical strength of nano-HAp and TiO2 samples sintered at high temperature was assessed in Simulated Body Fluid (SBF) having ionic concentration as that of human plasma. Biodegradation and change in mechanical properties of the sintered samples when kept in SBF and maintained in a dynamic condition were studied in terms of weight loss, change in Vickers hardness and biaxial flexural strength as a function of time. Highly crystalline HAp powder was achieved after microwave synthesis with average particle size in the range of 10-20 nm which was further confirmed by HR-TEM and SEM. Calcination of the synthesized powder at 500[degrees]C for 2 h increased the average particle size to 21 nm. EDS confirmed the elemental composition of the powder. FTIR analysis showed the presence of phosphate band which confirmed the presence of HAp at high temperature. TG analysis showed 23% weight-loss upon heating up to 1200[degrees]C, contributed by the removal of adsorbed and possible lattice water, decarboxylation of HAp or condensation of HPO42- releasing water. HAp along with [Beta]NaCaPO4 and Na3Ca6(PO4)5 was observed at 950[degrees]C, 1100[degrees]C and 1200[degrees]C. Density of HAp samples continued increasing with the increase in temperature from 1100[degrees]C to 1250[degrees]C and sintered density of 2.88 g/cc was obtained at 1250[degrees]C. Hardness and Biaxial strength of the HAp samples increased with temperature and maximum hardness value of 249.53 [plus or minus] 3.98 HV and biaxial flexural strength of 52.07 [plus or minus] 4.96 MPa were observed for samples sintered at 1250[degrees]C. Biaxial strength and hardness of TiO2 samples increased with temperature. Maximum biaxial flexural strength of 125.5 [plus or minus] 11.07 MPa and maximum hardness of 643.27 [plus or minus] 7.96 HV were observed for the TiO2 sample sintered at 1500[degrees]C which was much more than that of sintered HAp samples. Decrease in mass, hardness and biaxial strength of HAp samples sintered at 1250[degrees]C and TiO2 samples sintered at 1400[degrees]C showed biodegradation in SBF, maintained in a dynamic state, as a function of time. Increase in mass was observed for the HAp samples in SBF during the fourth week.

Microemulsions are nanostructured dispersions that have unique properties, which make them attractive for applications such as biomaterials, drug delivery, and nanoparticle synthesis. The behaviour of hydrocarbon microemulsions and their applications have been extensively studied, however, there have been very few studies in the preparation or the polymerization of silicone microemulsions. Silicone microemulsions offer a unique template by which to create novel nanoporous silicone elastomers and/or hydrogels. The prevalent use of silicones in biomaterials, coatings, and personal care (to name a few) make the development of silicone-based microemulsions of particular interest. The aim of thesis research was to polymerize silicone microemulsions and to understand the factors that contribute to retaining initial template morphology in the polymeric product. Chapter Two of this thesis focuses on the preparation of silicone microemulsions containing a non-polymerizable and polymerizable trisiloxane surfactant, respectively. Formulations were prepared and characterized by electrical conductivity to determine the microemulsion structure type. Formulations located in the bicontinuous region of the phase diagram were polymerized, producing transparent silicone elastomers. The focus of Chapter Three was to determine the tolerance of silicone microemulsions to selected chemistry that is relevant to silicone polymers. Previous work done in the field of polymerizing silicone microemulsions has been based on radical polymerization processes. There are no reports that examine the polymerization of a silicone microemulsion by room temperature vulcanization (RTV), a common process for creating silicone elastomers. We aimed to better understand the effects of RTV cure on morphology retention from the liquid to polymeric product to determine if this type of chemistry could be used in the formation of nanoporous silicone elastomers either on its own or in conjunction with a radical polymerization process. In order to understand the effects of an RTV process on polymer structure, we examined the effect of the variable components (necessary for the RTV cure) on the silicone microemulsion template. Small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were used as tools to characterize materials prior to and after cure. Silicone microemulsions that were cured using the RTV process produced nanoporous polymeric elastomers, however, the initial bicontinuous microemulsion template was not retained. RTV cured microemulsions retained the bicontinuous structure if the RTV cure was preceded by a photopolymerization reaction to “lock-in” surfactant monomers at the oil/water interface. Chapter Four explores the use of silicone microemulsions as a reaction vehicle in the formation of nano-TiO2 particles. The focus of this chapter was the exploitation of microemulsion droplets and bicontinuous structures that were designed to retard TiO2 particle formation in situ. Titanium isopropoxide (TTIP) was incorporated into silicone microemulsions containing varying amounts of water. Interactions between TTIP and the trisiloxane polyether surfactant result in the formation of a compound containing a Ti4+, coordinated to silicone surfactant molecules via a polyether linkage. Titania forms in situ as water is titrated into the surfactant/oil mixture, resulting in the formation of a microemulsion. The formation of TiO2 was monitored by UV-Vis spectroscopy and the TiO2 particles were characterized using transmission electron microscopy. / Thesis / Doctor of Philosophy (PhD) / This thesis is about the chemical modification and polymerization of nanostructured liquids in the form of silicone microemulsions to create nanoporous silicone elastomers (nano is one billionth, 10-9, so 1 nanometer = 1 billionth of meter). Despite the highly prevalent commercial use of silicones and the utility of silicone elastomers, little is known about the polymerization of silicone microemulsions to create nanoporous materials. The first goal of this thesis was to polymerize silicone microemulsions, using methods that have been previously used in the polymerization of hydrocarbon microemulsions. Silicone microemulsions were successfully polymerized using a reactive surfactant and rigidification of the oil phase was achieved using common silicone crosslinking chemistry. The second goal was to understand how the type of chemistry affects changes in structure upon transition from liquid microemulsion to solid polymer. Nanostructuring was retained in polymerized microemulsions both with and without oil phase polymerization. Finally, the third goal was to exploit silicone microemulsion domains to control titanium dioxide particle formation. Particle formation was slowed as a result of domain constricted particle growth.

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