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1
Ki, Jun-Wan. "Titanium Sponge on Titanium Substrate for Titanium Electrolytic Capacitor Anodes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1113244951.
Testo completo
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Toner, Andrew Joseph. "Titanium-aluminium and titanium-alkyl Schiff base complexes." Thesis, Manchester Metropolitan University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361566.
Testo completo
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Eriksson, Mirva. "Spark plasma sintering and deformation behaviour of Titanium and Titanium/TiB2Spark plasma sintering and deformation behaviour of Titanium and Titanium/TiB2 composites." Licentiate thesis, Stockholms universitet, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26122.
Testo completoAbstract (sommario):
Titanium has been used as a model substance to study how it behaves in a SPS apparatus when heating rate and/or pressure were varied during the sintering and deformation process. The sintering and deformation of Ti in SPS were compared with that occurring in the conventional hot pressing (HP) in order to reveal if there are any positive effects added by the use of SPS. The ductility of Ti was explored in order to understand the sintering and deformation of (Ti) x (TiB2)1-x composites with x = 0.05, 0.1, and 0.2, respectively, expressed in mol ratio. The temperature difference (DT) between the monitored and the temperature that the samples are exposed to was evaluated. It was noticed that Ti can be sintered at relatively low temperatures. High heating rate implied that the onset temperatures of the sintering and deformation processes decreased. Increasing pressure did not affect the onset temperature but revealed that the deformation of Ti is different if the experiments are conducted within the stability region of the a -phase region of Ti or if the deformation takes place in a temperature region that covers both a-and b-phase areas, i. e. the use of high pressures implied a one step deformation process while the use of low implied that the main part of the deformation took place in the b-phase region. (Ti) x (TiB2)1-x composites were prepared to full densities at 1500 °C using a holding time of 3 min and pressure of 50 MPa. During the SPS sintering the composite with x= 0.2 revealed the presence of TiB due to the reaction Ti + TiB 2 -> 2TiB while the composites with low x values did not show any formation of TiB. The formation of TiB impaired the mechanical properties. The deformation of composites was very difficult. Their deformability increased with increasing x and temperature as well as pressure. During the deformations of pre-sintered samples TiB was formed in all of the composites.
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Nishiguchi, Shigeru. "Bone-bonding Abilities of Alkali- and Heat-treated Titanium and Titaniumu Alloys." Kyoto University, 2000. http://hdl.handle.net/2433/180814.
Testo completo
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Adipuri, Andrew Materials Science & Engineering Faculty of Science UNSW. "Chlorination of Titanium Oxycarbide and Oxycarbonitride." Publisher:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44405.
Testo completoAbstract (sommario):
The project undertook a systematic study of chlorination of titanium oxycarbide and oxycarbonitride with the aim to develop further understanding of kinetics and mechanisms of the chlorination reactions. The project studied titania, ilmenite ores, and synthetic rutile reduced by carbon in argon and nitrogen and chlorinated at different temperatures, gas flow rates and compositions. Chlorination of titanium suboxides, iron and impurities in ilmenite was also examined. Chlorination of titanium oxycarbide Ti(O,C) or oxycarbonitride Ti(O,C,N) can be implemented at 200 to 400 deg.C, while the commercial chlorination process in the production of titanium metal or titania pigment requires 800 to 1100 deg.C. This makes chlorination of Ti(O,C) or Ti(O,C,N) an attractive technology in processing of titanium minerals. Chlorination reaction is strongly exothermal, which increased the sample temperature up to 200 deg.C above the furnace temperature. The chlorination of Ti(O,C) or Ti(O,C,N) was ignited at 150 deg.C to 200 deg.C depending on the sample composition. Their chlorination at 235 deg.C to 400 deg.C was close to completion in less than 30 min. The chlorination rate of titanium oxycarbide or oxycarbonitride increased with increasing gas flow rate. Sample composition had a significant effect on the extent of chlorination. The optimum results were obtained for titanium oxycarbide or oxycarbonitride produced with carbon to titania molar ratio of 2.5; these samples contained no detectable excess of carbon or unreduced titanium suboxides. In chlorination of reduced ilmenite ores and synthetic rutile, Ti(O,C) or Ti(O,C,N), metallic iron and Ti2O3 were chlorinated. The rate and extent of chlorination of titanium increased with increasing carbon to TiO2 ratio. Chlorination of Ti2O3 was slow relative to Ti(O,C) or Ti(O,C,N) and iron; chlorination of impurity oxides such as MgO, SiO2 and Al2O3 was not observed. The project also examined chlorination of Ti(O,C) or Ti(O,C,N) in ilmenite ore and synthetic rutile after removal of iron, which was achieved by aerated leaching of reduced samples in heated flask containing 0.37 M of ammonium chloride solution. Iron removal from the ilmenite ore or synthetic rutile resulted in higher rate and extent of chlorination of titanium oxycarbide or oxycarbonitride.
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Yuan, Fei (Fred) Materials Science & Engineering Faculty of Science UNSW. "Properties of titanium matrix composites reinforced with titanium boride powders." Awarded by:University of New South Wales. Materials Science & Engineering, 2007. http://handle.unsw.edu.au/1959.4/40750.
Testo completoAbstract (sommario):
Metal matrix composites can produce mechanical and physical properties better than those of the monolithic metal. Titanium alloys are widely used matrix materials as they can offer outstanding specific strength, corrosion resistance and other advantages over its competitors, such as aluminium, magnesium and stainless steel. In past decades, titanium matrix composites served in broad areas, including aerospace, military, automobile and biomedical industries. In this project, a revised powder metallurgy method, which contains cold isostatic pressing and hot isostatic pressing, was adopted to refine the microstructure of monolithic titanium. It was also used to manufacture titanium matrix composites. TiH2 powder was selected as the starting material to form Ti matrix and the reinforcements were sub-micron and nano-metric TiB particles. Mechanical properties and microstructure of commercial titanium composites exhaust valves from Toyota Motor Corporation have been studied as the reference of properties of titanium composites manufactured in this project. It has been shown that tensile strength and hardness of exhaust valves increase about 30% than those of similar matrix titanium alloys. Examination on powder starting materials of this project was also carried out, especially the dehydrogenation process shown in the DSC result. Mechanical properties and microstructures of titanium matrix composites samples in this project, as related to the process parameter, have also been investigated. The density of these samples reached 96% of theoretical one but cracks were found through out the samples after sintering. Fast heating rates during the processing was suspected to have caused the crack formation, since the hydrogen release was too fast during dehydrogenation. Hardness testing of sintered samples was carried out and the value was comparable and even better than that of commercial exhaust valves and titanium composites in literature. Microstructure study shows that the size of reinforcements increased and the size of grains decreased as the increasing amount of TiB reinforcements. And this condition also resulted in the increasing amount of the acicular alpha structure.
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Rasool, Ghulam. "Tribo-corrosion maps for steels, titanium and titanium carbide materials." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24939.
Testo completoAbstract (sommario):
In this project, research work was carried out on the tribo-corrosion behaviour of titanium carbide composite coatings produced by Tungsten Inert Gas (TIG) welding torch melting process on steel and titanium substrates. The integrity of TiC composite coatings were checked and analysed on the substrates. The effects of change in sliding speeds and normal loads on wear behaviours were investigated for dry sliding conditions and tribo-corrosion maps were constructed with a tribo-system approach. The work was carried out in the following phases: In phase I, a fundamental study of the wear behaviour of two steels of different Cr contents and hardness were carried out. Pin-on-disk apparatus was used for testing 303stainless steel (303SS) disks and 8620 low alloy steel pins. For 303SS adhesive wear and tribo-oxidation were predominated at relatively low sliding speeds and adhesive wear was predominated at high sliding speeds and normal loads. In contrast, oxidative wear was more prevalent for the low alloy steel. Wear mapping approaches were undertaken to represent the transitions in wear modes and wear mechanisms as a function of sliding speeds and applied loads. The different wear maps generated for the pins and disks were discussed in the context of the wear mechanisms observed in the tribological contact. In phase II, dry sliding wear tests were carried out on 303SS disks (uncoated and coated with TiC composite coatings) against alumina balls as a counterface on pin-on-disk configuration. The composite coatings increased the surface hardness hence the sliding wear resistance of the 303SS substrate. Wear maps for both uncoated and coated materials were developed on the basis of tests results. These maps show that the mild wear regime for the composite coating was expanded to a higher range of sliding speeds and normal loads. For the composite coating, an additional wear mode transition i.e. from the mild to very mild regime occurred at low sliding speeds and normal loads. In phase III, experimental work was carried out on a pin-on-disk sliding wear testing rig on hardened steel (A.I.S.I. 0-1-Ground Flat Stock) disks and titanium (Ti) uncoated and coated pins with titanium carbide (TiC) composite coatings. For uncoated Ti and hardened steel tribo-couple, pins' material was transferred to disks and covered the wear tracks almost for each combination of sliding speed and normal load. High wear of Ti was found against hardened steel. Adhesive wear was prevalent for Ti pins along with abrasive, plastic deformation and delamination against hardened steel disks. While for the Ti base TiC composite coatings against hardened steel different wear behaviour observed. The composite coating increased the surface hardness hence the sliding wear resistance of the Ti substrate. Dry sliding wear behaviour of hardened steel disks was characterized by abrasive-oxidative wear at lower normal load while adhesive-oxidative wear was predominated at high normal load with iron oxide transfer to the coated pins for the range of sliding speed. In contrast, micro-abrasion and oxidative wear were predominated for the TiC composite coatings pins along with very mild adhesive-abrasive wear. A tribo-system approach was adopted to investigate the wear behaviour of TiC coatings and hardened steel against each other. Wear maps for both uncoated and coated materials were constructed on the basis of tests results. The tribo-corrosion maps show that due to TiC composite coating wear resistance of the substrate was increased. Higher tribo-corrosion resistance of the TiC composite coatings was found on Ti substrate than that of 303SS substrate. Moreover, the surfaces treated with TiC coatings by TIG welding torch as heat source, expanded the mild wear regime to a higher range of sliding speeds and normal loads with creation of a new wear regime i.e. very mild wear and elimination of severe wear regime.
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Jeffers, Elizabeth Ann. "Reaction Synthesis of Titanium Aluminide / Titanium Diboride in-Situ Composites." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/35367.
Testo completoAbstract (sommario):
Reaction synthesis is a processing technique where the thermal activation energy needed to form a compound is provided by the exothermic heat of formation of the thermodynamically stable product. This type of synthesis has been used to form a variety of ceramics, intermetallics, and in-situ composites. In this work, the effects of changing the stoichiometry of the titanium aluminide matrix, and the effects of extrinsic reaction variables on the behavior of the reaction were studied and compared to theoretical predictions. It was shown that changing the stoichiometry of the titanium aluminide did have an effect on the measured heat of reaction; however this did not match the prediction. Changing the extrinsic variables of titanium and aluminum particle sizes also showed a significant effect on the behavior of the reaction.<br>Master of Science
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Cairns, Malcolm. "Titanium particle combustion." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86572.
Testo completoAbstract (sommario):
In order to increase the validity of numerical models of the detonation of heterogeneous titanium explosives, experimental results are needed. The combustino of titanium is studied using two experimental techniques. The first technique is the study of the burn time for a single particle over a wide range of initial diameters while altering the oxygen concentration. To accomplish this a new flat flame burner to study particle burn time has been designed. Luminous tracks caused by the light emitted by the combustion of the particles are analyzed and burn time is inferred. Burn time in air and in an oxygen enriched atmosphere were determined. A second experiment involves the study of large scale detonation of heterogeneous charges. The charges are filled with nitromethane and a packed bed of titanium particles. The titanium particles varied in morphology and particles size. A critical charge diameter for charge ignition (CDPI) was found for irregularly shaped particles but was not found for spherical particles.<br>Pour augmenter la validit des modles numriques sur dtonation d'explosifs htrognes contenants du titane , des rsultats exprimentaux sont ncessaires. Le combustino de titane est tudi en utilisant deux techniques exprimentales. La premire technique est l'tude du temps brle pour une particule sur une large gamme de diamtres initiaux en changeant la concentration d'oxygne. Pour l'accomplir un nouveau brleur de flamme plat pour tudier la particule brle le temps a t conu. Les empreintes lumineuses provoques par la lumire mise par la combustion des particules sont analyses et brlent le temps est dduit. Brlez le temps dans l'air et dans l'atmosphre enrichie d'un oxygne ont t dtermins. Une deuxime exprience implique l'tude de grande dtonation d'chelle de charges htrognes. Les charges sont remplies de nitromethane et un lit emball de particules de titane. Les particules de titane variaient dans la grandeur de particules et la morphologie. Un diamtre de charge critique pour l'ignition de charge (CDPI) a t trouv pour les particules irrgulirement en forme de, mais n'a pas t trouv pour pour les particules irrgulirement en forme de mais n'a pas t trouv pour les particules sphriques.
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Bettley, Alison. "Electroplated titanium coatings." Thesis, Open University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305065.
Testo completo
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Williams, Niel Hamilton. "Titanium isotope cosmochemistry." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/titanium-isotope-cosmochemistry(571ae148-1673-4b85-bc10-937284bb53fc).html.
Testo completoAbstract (sommario):
High precision measurements of Ti isotopes within terrestrial and extra-terrestrial materials were made in order to investigate the processes at work within the early solar system. Variations of Ti isotopes also enabled the investigation of the specific stellar sources that created the material that formed the solar system. Titanium was chosen as it is a refractory element, relatively resistant to secondary processes and found abundantly in all solar system materials. Measurements were performed using a Thermo Fischer Neptune MC-ICPMS at the Open University, Milton Keynes. Various samples of carbonaceous chondrites, ordinary chondrites, enstatite chondrites, achondrites, lunar, terrestrial and early solar system components were analysed. Mass independent measurements of various solar system materials revealed a correlation between ε50/47Ti49/47 and ε46/47Ti49/47 defining a best line with a slope of 5.34 ± 0.34. The correlation indicates that solar system materials contain nucleosynthetic components that match a SNII stellar source. Utilising aliquots previously analysed for Zr isotopes for Ti isotope analyses revealed a correlation between ε50/47Ti49/47 and ε96/90Zr94/90 for the carbonaceous chondrites that is controlled by the CAI content of the particular carbonaceous chondrite group. Step wise dissolution of ordinary chondrites and carbonaceous chondrites revealed multiple nucleosynthetic Ti components contributing to the solar system. Stepwise leachate dissolutions were conducted on the carbonaceous chondrites Allende, Murchison and Orgueil to compliment the study of the same samples for Zr by Schönbächler et al. (2005). In addition, sample aliquots of QUE 97008 and Murchison from the work of Qin et al. (2011) were also investigated for Ti. The two investigations allow the comparison of Ti in different phases to be compared with other isotope systems such as Zr (Schönbächler et al. 2005) and Cr, Sr, Ba, Sm, Nd and Hf (Qin et al. 2011).Mass dependent fractionation and absolute nucleosynthetic anomalies of Ti within solar system materials was determined by utilising the double spike procedure. Mass dependent analysis enabled the Stable isotope composition of terrestrial materials to be investigated, revealing mass dependent fractionation between terrestrial basalts and andesite’s. Utilising the double spike procedure also enabled the calculation of absolute nucleosynthetic anomalies for Ti within solar system materials. The absolute nucleosynthetic anomalies data revealed that CAI’s contain two different compositions with one representing an exotic stellar source and the other representing the mainstream solar system composition.
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Turner, Sam. "Titanium milling strategies." Thesis, University of Sheffield, 2009. http://etheses.whiterose.ac.uk/15127/.
Testo completoAbstract (sommario):
This thesis explores the subject of titanium milling and identifies the need for development of titanium milling strategies to address the key process limitations of chatter and tool wear. These subjects are typically studied in isolation and little work has previously been undertaken on titanium milling dynamics. Titanium is often perceived as difficult to machine as the very properties such as high strength at high temperature and low thermal conductivity that make it an attractive engineering material can cause rapid tool wear and limit process parameters. Titanium alloys are increasingly popular within the aerospace industry due to the high strength to weight ratios and titanium and carbon fibre composites have replaced many steel and aluminium components within aerostructures. Titanium is still seen by many as expensive to process and there is not the same degree of understanding and process optimisation within the machining industry as there is for aluminium and steel alloys. The literature review considers both advances in titanium tool wear mechanisms and research into machining dynamics. From the literature review three research hypotheses are developed around the knowledge gaps pertaining to titanium milling stability and process optimisation. The limitations on milling performance and productivity are considered and three areas are identified where the research could be advanced to improve titanium milling productivity through manipulation of parameters and tool geometry, these areas are pocketing strategies, special tooling geometries and process damping. A method for controlling radial immersion for pocketing strategies is developed and it is proven that through control of parameters and toolpaths that tool life and productivity can be optimised and controlled. A study is then undertaken into the performance and modelling of variable helix end mills to explore the hypothesis that the tools will outperform standard and variable pitch cutters and that the performance can be modelled. As part of the validation process an analysis of the linearity of machine tool dynamics is undertaken and it is demonstrated that under speed and load, spindle and machine tool frequency responses can differ from those measured in the static condition. The final part of the research investigates process damping performance and sensitivity to cutting tool geometry and feed rates. A method for evaluating process damping performance is developed and through optimisation of tool geometry and feed per tooth increases in productivity up to 17 fold are demonstrated. A method is then presented for tuning machine tool dynamics to optimise process damping performance and stabilise sub optimum tooling and machine tools. The three core strands of the thesis are brought together and demonstrated in an aerospace case study. Through application of the techniques developed in the thesis a titanium aerostructural component is machined at the same rates as an equivalent steel component and at less than 50% of the planned titanium milling process time.
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Mariscal, Muñoz Eduardo [UNESP]. "Diferenciação de osteoblastos cultivados sobre superfícies de titânio modificados por irradiação com laser Yb: YAG pulsado de alta potencia." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/97275.
Testo completoAbstract (sommario):
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mariscalmunoz_e_me_arafo.pdf: 3090290 bytes, checksum: 16c5f9ca343ea1d3e9b942ecb341ffbb (MD5)<br>A osseointegração, requisito indispensável para o sucesso dos implantes dentários, é um processo lento, caracterizado, sequencialmente, pelas etapas de adesão, diferenciação e proliferação celular, bem como pela aposição e mineralização da matriz óssea depositada por osteoblastos. Acelerar o processo de osseointegração significa reduzir o tempo de espera para a aplicação segura de uma carga funcional sobre os implantes de titânio (Ti). Sabe-se que vários fatores, tal como a topografia da superfície do Ti, influenciam diretamente o processo de osseointegração. Assim, desde que foi demonstrado que alguns padrões específicos de superfície do Ti são capazes de bio-estimular osteoblastos, favorecendo e acelerando a osseointegração, diversas técnicas de baixo custo, rápida execução e altamente reproduzíveis, tem sido propostas para tratar a superfície dos implantes. Desta maneira, o objetivo da presente pesquisa foi avaliar a capacidade de superfícies de Ti, modificadas com laser pulsado de alta potência (L) ou usinadas (U), de estimular a diferenciação e maturação de células obtidas de calvária de camundongos cultivadas sobre elas. Para isto, foram realizados ensaios laboratoriais para determinar a atividade mineralizadora das células (coloração com vermelho de alizarina e fosfatase alcalina), o metabolismo (MTT assay) e morfologia celular (MEV). A fim de melhor caracterizar a diferenciação de osteoblastos, foi realizada a reação de polimerização em cadeia (PCR) quantitativa em tempo real para analisar a expressão, pelas células cultivadas sobre as superfícies de Ti, de genes que codificam os fatores de transcrição Runx2 e Sp7 e proteínas específicas da matriz extracelular mineralizada...<br>The osseointegration, which plays a fundamental role in the dental implantation success, is characterized by cell adhesion, differentiation, proliferation as well as deposition and mineralization of of bone matriz by osteoblasts. To make the osseointegration process faster means reducing the period to apply a safe functional stress on the titanium (Ti) implants. A number of factors, such as the topographical surface of Ti enhances the osseointegration process. Different Ti surface treatments capable of bio-estimulating osteoblasts to accelerate the osseointegration have been evaluated. Current studies have shown that osseointegration of Ti devices is enhanced by surface roughness. In this way, the aim of the present investigation was to assess the capacity of Ti surfaces irradiated with high potency laser (L) or polished (U) to stimulate the differentiation and maturation of cells obtained from calvarian bone of mouse. Then, laboratorial protocols to evaluate the mineralizing cell activity (alizarin red assay), cell metabolism (MTT assay) as well as the morphology (SEM) of cells cultured on the Ti surfaces were carried out. To better characterize the osteoblast differentiation, the real time qPCR for expression of genes that code to the transcription factors Runx2 and Sp7 were performed. Additionaly, this protocol was also used to assess specific proteins of extracellular matrix (Spp1, Alpl, e Col1a1). The numeric data were subjected to statistical analysis. Our data demonstrated that the Ti surface L improved the osteoblast maturation capacity of calvarial osteoblasts grown over this surface. Scanning electron microscopy (SEM) revealed spheres and protrusions created by laser treatment. Laser profilometry showed a disordered surface with micrometric and/to nanometric scales features (Ra = 10.57μm). When compared to polished... (Complete abstract click electronic access below)
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Faverani, Leonardo Perez [UNESP]. "Efeitos de diferentes concentrações de dextrose e lipopolissacarídeo no comportamento corrosivo da liga Ti-6Al-4V com superfície usinada e tratada com duplo ataque ácido." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/101072.
Testo completoAbstract (sommario):
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000737176.pdf: 2233924 bytes, checksum: be9f98eec022d58f2c75519afa00ec37 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Objetivos: Avaliar o comportamento corrosivo da liga Ti-6Al-4V em função de sua superfície polida ou condicionada por meio de duplo ataque ácido, em simulador de fluidos corporais (SFC) com diferentes concentrações de dextrose (0; 5mM; 7,5 mM e 15 mM) e lipopopolissacarídeo (LPS) (0; 0,15 μg/mL; 15 μg/mL; 150 μg/mL), usados isolados ou associados. Materiais e Métodos: Discos de liga Ti-6Al-4V (2 mm de espessura e 15 mm de diâmetro) foram confeccionados com diferentes padrões de superfície. Para o ensaio eletroquímico (n=3), testes padrões como potencial de circuito aberto, espectroscopia de impedância eletroquímica (EIE) e teste potenciodinâmico foram conduzidos em solução de fluido corpóreo (SBF) com diferentes concentrações de dextrose e LPS. As superfícies dos discos foram caracterizadas pela microscopia eletrônica de varredura (MEV), microscopia de força atômica (MFA), e por meio da rugosidade de superfície e da microdureza. Os dados quantitativos foram analisados pelo teste de correlação de Pearson e T-teste independente, com nível de significância de 5%. Resultados: Nos parâmetros de corrosão, houve forte correlação do LPS com os valores de Ipass (densidade de corrente de passivação), Cdl (capacitância) e Rp (resistência de polarização) (p<0,05) para o titânio (Ti) com tratamento de superfície por duplo ataque ácido. A associação de dextrose e LPS foi correlacionada com Icorr (densidade de corrente de corrosão) e Ipass (p<0,05). Em relação à cinética de corrosão, os grupos tratados com ácido apresentaram aumento significante nos valores de Cdl e redução nos valores de Rp (P<0,05, T-teste). Quanto à topografia, houve aumento da rugosidade de superfície para ambas as superfícies (R2=0,726, p=0,0001 para Ti polido; R2=0,405, p=0,036 para Ti ácido). A microdureza do Ti polido diminuiu (p<0,05) e do Ti ácido aumentou (p=0,0001). A MFA...<br>Objectives: To analyse the corrosion behavior of Ti-6Al-4V with different surfaces (machined and modified by treatment with double acid-etching), on simulator body fluids (SBF) with different concentrations of dextrose (0; 5 mM, 7.5 mM and 15 mM) and lipopolysaccharide (LPS) (0; 0.15 μg/mL; 15 μg/mL; 150 μg/mL), used isolated or in combination. Materials and Methods: Ti-6Al-4V disks (2 mm in thickness and 15 mm in diameter) were fabricated with different surfaces. For electrochemical assay (n = 3), open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic tests were conducted in SBF with different concentrations of dextrose and LPS. The surfaces of the disks were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and by surface roughness and microhardness. Data were analyzed by Pearson correlation and independent t-test at a significant level of 5%. Results: For the corrosion parameters, a strong correlation of LPS with Ipass (passivation current density), Cdl (capacitance) and Rp (polarization resistance) values (P <.05) for Ti surface treated by double acid- etching was noted. The combination of dextrose and LPS was correlated with Ipass and Icorr (corrosion current density) (P <.05). Regarding the corrosion kinetics the acid-treated groups showed significant increase in Cdl values and reduced values of Rp (P <.05, T-test). In terms of topography, there was an increase in surface roughness for both surfaces (R2 = 0.726, p = 0.0001 for machined Ti, R2 = 0.405, p = 0.036 for Ti acid). The machined Ti exhibited reduction in microhardness (P <.05), while Ti acid showed increased microhardness (p = 0.0001) vs baseline. The AFM showed changes in the microstructure of Ti by increasing the thickness of surface mainly in the association of dextrose and LPS. Conclusions: The combination of dextrose ...
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Almussa, Amanda Fahning Magno [UNESP]. "Avaliação in vivo e in vitro do efeito do tempo sobre molas fechadas de níquel-titânio." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/104497.
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almussa_afm_dr_arafo.pdf: 1982978 bytes, checksum: 078c30ee2ec08d13b4ca6d31af723b59 (MD5)<br>Determinar in vivo e in vitro o efeito do tempo sobre as propriedades mecânicas de molas helicoidais fechadas de níquel-titânio. Métodos: Três artigos científicos foram redigidos e utilizados para a avaliação dos propósitos apresentados. Resultados: No artigo 1 (in vivo), o tempo e a ativação influenciaram significantemente a taxa de superelasticidade (SE) e a força média do platô clínico superelástico (FP) quando o perfil total das molas foi avaliado (p<0,001). Foi detectada uma interação significante entre tempo e ativação nas variáveis taxa de SE (p<0,001) e FP (p=0,013). No artigo 2 (in vitro), o tempo influenciou significantemente a FP e a taxa de SE quando o perfil total das molas foi avaliado (p<0,001). A ativação influenciou significantemente a taxa de SE (p<0,001), não influenciando a FP (p=0,218). Foi detectada uma interação significante entre tempo e ativação na variável taxa de SE (p=0,020), o que não ocorreu na variável FP (p=1,00). No artigo 3 (in vivo), o uso clínico e a ativação influenciaram significantemente a deformação das molas (p<0,001). Foi detectada interação significante entre os fatores tempo e ativação na variável deformação (p<0,001). Conclusões: Após 6 meses de uso clínico, as molas apresentaram diminuições significantes nas taxas de SE em até 52%, nas FP em até 88% e aumento da deformação em até 1,26 mm. Laboratorialmente, os efeitos nas FP foram maiores nos dois primeiros meses e depois se estabilizaram, já as taxas de SE não apresentaram diferenças nos dois meses iniciais, aumentando nos seguintes. Desta forma, a reutilização das molas avaliadas neste estudo seria desaconselhada.<br>Determine in vivo and in vitro the time effect on the mechanical properties of nickel-titanium closed coil springs. Materials and Methods: Three research papers were written and analyzed for the evaluation of the aims presented. Results: In first paper (in vivo), time and the activation significantly affected superelasticity (SE) rate and the average force of the superelastic clinical plateau (FP) when the total profiles of the springs were evaluated (p<0,001). A significant interaction between time and activation was detected for the SE rate (p<0,001) and FP (p=0,013) variables. In second paper (in vitro), time significantly affected FP and SE rate when the total profiles of the springs were evaluated (p<0,001). Activation significantly affected the SE rate (p<0,001), but not the FP (p=0,218). A significant interaction between time and activation was detected for the SE rate variable (p=0,020), but not for the FP variable (p=1,00). In third paper (in vivo), the clinical use and activation significantly affected the springs deformation (p<0,001). A significant interaction between time and activation was detected for the deformation variable (p<0,001). Conclusions: After six months of active clinical use, the analyzed springs presented a significant decay on their SE rates up to 52%, on FP up to 88% and increase in deformation up to 1,26 mm. In the in vitro study, the effects on FP were higher in the first two months and then stabilized, and the SE rates didn’t differ in the two initials months, increasing in the following. This way, reuse of the springs evaluated in this study would be inadvisable.
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Jones, Kayleigh Elizabeth. "Interactions of Microbial Siderophores with Titanic Ions and Titanium-Bearing Minerals." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/434374.
Testo completoAbstract (sommario):
Chemistry<br>Ph.D.<br>Transition metals play an important role in many biological processes. Iron is essential for almost every organism, but its bioavailability is limited due to the low solubility of Fe(III) in aqueous environments. Microbial siderophores help solubilize and sequester iron(III). In solution, siderophores like desferrioxamine B (DFOB) are also avid binders of Ti(IV). Ti(IV) is chemically similar to Fe(III), and the use of usually-inert TiO2 is increasing in products such as sunscreens and paint. The surface of titanium metal in joint replacements and implants is oxidized to form TiO2. Microbial siderophores bind to normally inert TiO2 and this binding can affect the solubility of Ti(IV). Dissolution might render Ti(IV) biologically available, and might interfere with Fe(III) biogeochemical cycling, as well as impact biofouling in marine, medicinal, and industrial applications. This research explores how siderophores interact with Ti(IV) in aqueous solutions and can solubilize Ti(IV) from the surface of solid TiO2. Spectrophotometric techniques and isothermal titration calorimetry were used to determine the speciation of Ti(IV)-DFOB and revealed a stability constant of log ~ 40 for Ti(IV)-DFOB when in competition with EDTA. Complementary computational methods were employed to predict the structure of Ti(IV)-DFOB, because no crystal structure has been determined thus far. Dissolution studies of TiO2 in the presence of DFOB were monitored by UV/Vis and ICP-OES to determine the kinetics of Ti(IV)-DFOB formation, using many different crystalline forms of TiO2 at several pH values. Kinetic data confirmed that dissolution of Ti(IV) with DFOB is a two-step process, with one faster, less extensive step and a slower step involving additional Ti(IV). Introduction of small organic acid-derived ligands such as oxalate, citrate, ascorbate and succinate changed the dissolution kinetics, suggesting a synergistic cooperation between oxalate-DFOB dissolution, while the others revealed inhibitory behavior. Exposure of sunscreen products that contained TiO2 to DFOB was also investigated to determine biological effects on siderophore binding. Further investigative studies were conducted using SEM and TEM to address the surface interactions of TiO2 with DFOB. Understanding these interactions is necessary to determine the effects of binding, the interactions of these complexes in aqueous environments and how they behave chemically in biological systems. Varying concentrations of Fe(III) and Ti(IV) were introduced together with DFOB to determine by using UV/Vis spectroscopy what metal will bind preferentially. ESI-mass spectra were obtained of these solutions to further confirm metal binding. DFOB-mediated mineral dissolution studies were explored by spectrophotometry and ICP-OES to determine the amount of soluble metal released into solution from -hematite Fe2O3, anatase TiO2 and pseudobrookite (Fe2TiO5) and the kinetics of dissolution. Finally, surface analysis was conducted using SEM and TEM to observe the effects of DFOB on the mineral phase. The demonstration that DFOB can bind Ti(IV) and solubilize TiO2 raised the question of whether other siderophores could potentially cause the same effects. Another biologically relevant siderophore is pyoverdine (PVD), found in Pseudomonas bacteria. It has been a strong focus since it was found to have many important roles ranging from virulence, cell to cell signaling, and quorum sensing for biofilm formation. Adhesion of these bacteria is often found on titanium surfaces. Biofilms form on biomedical titanium implants and biologically induced corrosion often occurs on TiO2 coated surfaces, such as on the sides of ships and the interior of pipes. PVD was isolated from bacterial culture and characterized. PVD was then exposed to Ti(IV) solutions and monitored by UV/Vis spectroscopy and fluorescence to characterize Ti-PVD formation and speciation, by using the same techniques as Ti-DFOB. Binding of Ti(IV) to PVD was determined using ITC to have a log ~51. Treatment of TiO2 with PVD yielded different results from those observed with DFOB. In particular, putative adsorption of PVD to the surface was seen rather than dissolution of Ti(IV). Growth of Pseudomonas in the presence of TiO2 showed enhanced growth rates and using Ti(IV) complexes, the effects on biofilm growth were determined. Understanding these interactions is necessary to determine the effects of binding, the interaction of these complexes in aqueous environments and how they behave chemically in biological systems.<br>Temple University--Theses
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Hurysz, Kevin Michael. "The processing of titanium hydride powders into uniform hollow spheres." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19502.
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Lee, Ho-Rim. "Comparative study of bond characteristics between titanium-titanium alloy and ceramic." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972776354.
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Hill, Davion M. "Microstructure and mechanical properties of titanium alloys reinforced with titanium boride." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1150402807.
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Flinn, C. "Photocatalytic reactions of alchohols on titanium dioxide and platinized titanium dioxide." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380187.
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Janzeer, Yasmeen. "Surface modification of titanium and titanium alloys to enhance bone healing." Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/surface-modification-of-titanium-and-titanium-alloys-to-enhance-bone-healing(04574a0c-b593-47ef-a002-608cbe67a04b).html.
Testo completoAbstract (sommario):
Titanium and Its alloys have been used for many years as the material of choice for fabrication of dental, orthopaedic and maxillofacial implants, due to their excellent mechanical properties, biocompatibility, and the ability to osseointegrate with the surrounding bone. In order to improve the bioactivity and osseointegration of titanium implants, especially in compromised bone, surface modification of the implant surface and surface coatings have been introduced. There are different kinds of surface modification, such as, grinding, plasma spraying, sputter coatings, and alkaline treatment. More significantly, immobilization of drugs, such as, bisphosphonates, played an important role in enhancing the bone healing process. The main aim of the study is to develop and identify a facile surface modification method of immobilizing bisphosphonate molecules on commercially pure titanium and its alloy. 10mm discs of commercially pure titanium (CpTi) and titanium-aluminium-vanadium (Ti-6Al-4V) alloy were subjected to different surface treatments experiments; 1) the CpTi and Ti64 alloy surfaces were invested in phosphate bonded investment (Deguvest) and heated up to 900°C simulating superplastic forming process (SPF) creating an interaction layer on the surface upon which they were subjected to immersion in simulated body fluid (SBF) for 7 and 10 days, 2) the titanium surfaces were subjected to alkali treatment with 5M NaOH at 60°C for 24 hours, further more immersed in SBF solution for 7 and 10 days, 3) immobilization of sodium alendronate bisphosphonate on the pre treated titanium surfaces using microseeding method, and 4) tethering of Bioglass® and sodium alendronate bisphosphonate on the titanium surfaces using the electrohydrodynamic spraying method. The surface characterization of the treated surfaces was assessed using scanning electron microscopy (SEM/EDAX), Raman spectroscopy, surface roughness profilometer, and atomic force microscopy (AFM). In vitro cellular bioactivity and cytotoxicity were evaluated on the treated surfaces. This study established that both the interaction layer and its treatment further with simulated body fluids created a favourable interaction layer on the titanium surfaces, which induced the formation of apatite like layer on the surfaces when soaked in SBF solution. The interaction layer so formed was stable and not lost after physical methods of cleaning, thus can be considered to be a quick and inexpensive method of surface modification of titanium implants, during processing itself, which can enhance the bone healing and result in improved osseointegration. The surface modification of CpTi and Ti64 achieved with SPF and sodium hydroxide treatment and further treatment with SBF were further used to immobilize alendronate successfully, which yielded a simple method of incorporating bisphosphonates on implant surfaces, without causing any damage to the drug as no heat treatment or chemical crosslinking was required. Based on the cellular response to the investment treated titanium samples, sodium hydroxide treated samples followed by SBF treatment it can be concluded that these surfaces provide favourable conditions for cell growth, proliferation and differentiation when compared to the non-invested samples.
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Gómez, Palomino Alejandro. "Titanium(IV) enolate chemistry applied to the stereoselective construction of C–C and C–O bonds. New ionic and radical processes." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/665122.
Testo completoAbstract (sommario):
In the present Thesis we continued a previous study of the nucleophilic character of titanium(IV) enolates. Particularly,we focused our attention on the analysis of substrate-controlled Michael additions to enones and other acceptors.Thus, the Michael addition of (S)-2-benzyloxy-3-pentanoneto enones was thoroughly evaluatedin Chapter 1. In the case of vinyl ketones, the best reaction conditions involved the use of two TiCl4 equivalents and afforded the 2,4-antiadducts as single diastereomers in excellent yields. In addition, the developed methodology was also evaluated with β- substituted enones, whose optimised conditions using TiCl4 and SnCl4 afforded the 2,4- anti-4,5-antiadducts with diastereoselectivities above 90:10 in all cases with good yields. Furthermore, the Michael addition of (S)-2-benzyloxy-3-pentanoneto α,β- unsaturated nitroalkenes was alsoanalysed inChapter 1. The use of two equivalents of TiCl4and aromatic nitroalkenes led to the 2,4-anti-4,5-syn adducts with excellent yields and diastereoselectivities. In turn, aliphatic nitroalkenes needed optimised conditions using TiCl4 and SnCl4 to afford the 2,4-anti-4,5-syn adducts in good diastereoselectivities and yields. Finally, the nitro group was converted into other useful functional groups.
Another objective of the first part of this thesis wasto re-evaluate the synthesis of the tetrahydropyran ring from the C1-C9 fragment of herboxidiene/GEX1A. Thus, in Chapter 2 we analysed the initial retrosynthesis of the C1-C9 fragment and studied the oxa-Michael cyclization. Finally, we designed two parallel sequences to improve the first synthetic approach.The stereoselective synthesis of the tetrahydropyran ring was successfully accomplished following two different approaches. In approach 1, the number of steps was increased, but the sequence pursued a fully stereoselective pathway taking advantage of the great selectivity offered by a dimethylpyrrole amide under acidic conditions attaining a 54% yield (46% for the original approach). In approach 2, the original sequence of reactions was followed, but the suppression of unnecessary purification operations and a final isomerisation step increased notably the yield up to 58% (39% for the original approach).
Keepingin mind the biradical character of certain titanium enolates, the second objective of this Thesis was to examine the uncommon radical reactivity of titanium enolates derived from chiral N-acyl oxazolidinones when exposed to radical reagents. In Chapter 3, the aminoxylation of chiral N-acyl oxazolidinones was improved using a chiral tert-butyl oxazolidinethionederived from tert-leucine. This chiral auxiliary provided the aminoxylated products as single diastereomers in all cases with excellent yields. Finally, the resulting adducts were transformed into synthetical useful intermediates. Furthermore, in Chapter 3 we also reported a highly stereoselective oxidation of titanium enolates from chiral N-acyl oxazolidinones with molecular oxygen. The direct hydroxylation of biradical titanium(IV) enolates derived from chiral oxazolidinones with O2 proved to be feasible. Thus, we described a novel approach for the synthesis of enantiomerically pure α-hydroxy carboxylic derivatives.
We describe in Chapter 4 a comprehensive search of compounds capable of participating in radical reactions, which involved a brief exploration of photoredox catalysis. Finally, such research led to the discovery of a new and highly
stereoselective alkylation with aliphatic diacyl peroxides. Decarboxylation of the diacyl peroxides from aliphatic acids promoted by the titanium enolates produced primary and secondary radicals and triggered the formation of the alkylated adducts as single diastereomers with excellent yields.<br>En la presente Tesis continuamos un estudio previo sobre el carácter nucleófilo de los enolatos de titanio(IV) en adiciones de Michael con control por sustrato. Así, la adición de Michael de (S)-2-benciloxi-3-pentanona a enonas y nitroalquenos se evaluó a fondo en el Capítulo 1. En el caso de las vinil cetonas, las mejores condiciones de reacción implicaban el uso de dos equivalentes de TiCl4 o un equivalente de TiCl4 y otro de SnCl4 y proporcionaban los aductos 2,4-anti-4,5-anti con rendimientos excelentes y diastereoselectividades superiores a 90:10. Además, la metodología desarrollada también se empleó con nitroalquenos α,β-insaturados, conduciendo a proporcionar los aductos de 2,4-anti-4,5-syn con buenas diastereoselectividades y rendimientos.
En el Capítulo 2 se reevaluó la retrosíntesis inicial del anillo tetrahidropiránico del fragmento C1-C9 del herboxidieno/GEX1A. La síntesis estereoselectiva del anillo de tetrahidropirano se logró con éxito siguiendo dos enfoques diferentes. En el primer enfoque, se aumentó el número de pasos, pero la secuencia siguió una ruta completamente estereoselectiva aprovechando la gran selectividad ofrecida por una dimetilpirrolamida en condiciones ácidas. En el segundo enfoque, se siguió la secuencia original, pero la supresión de operaciones de purificación innecesarias y la inclusión de una etapa de isomerización final aumentaron notablemente el rendimiento.
El segundo objetivo de esta Tesis fue examinar la reactividad radical poco común de enolatos de titanio derivados de N-acil oxazolidinonas quirales cuando se exponen a reactivos radicalarios. Así, en el Capítulo 3, la aminoxilación de N-acil oxazolidinonas quirales se mejoró usando una tiazolidintiona de tert-butilo quiral derivada de tert-leucina que proporcionó los productos aminoxilados como únicos diastereómeros con rendimientos excelentes. Además, en el Capítulo 3 también llevamos a cabo una hidroxilación directa altamente estereoselectiva de enolatos de titanio a partir de N-acil oxazolidinonas quirales con oxígeno para la síntesis de derivados α-hidroxicarboxílicos enantioméricamente puros.
En el Capítulo 4 describimos una búsqueda exhaustiva de compuestos capaces de participar en reacciones radicales, lo que implicó una breve exploración de la catálisis fotoredox. Finalmente, tal investigación llevó al descubrimiento de una nueva alquilación altamente estereoselectiva con peróxidos de diacilo alifáticos que conducía a la formación de los aductos alquilados como diastereómeros únicos con rendimientos excelentes.
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Barnett-Ritcey, Dwayne D. Elbestawi Mohamed Abdel Aziz. "High-speed milling of titanium and gamma-titanium aluminide: An experimental investigation /." *McMaster only, 2004.
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Strutt, Elizabeth R. "Combustion synthesis, structure and transformation characteristics of titanium carbide-nickel titanium composites /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3129952.
Testo completo
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Eriksson, Mirva. "Spark plasma sintering and deformation behaviour of Titanium and Titanium/TiB2Spark plasma sintering and deformation behaviour of Titanium and Titanium/TiB2 composites." Licentiate thesis, Stockholm University, Department of Physical, Inorganic and Structural Chemistry, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26122.
Testo completoAbstract (sommario):
<p>Titanium has been used as a model substance to study how it behaves in a SPS apparatus when heating rate and/or pressure were varied during the sintering and deformation process. The sintering and deformation of Ti in SPS were compared with that occurring in the conventional hot pressing (HP) in order to reveal if there are any positive effects added by the use of SPS. The ductility of Ti was explored in order to understand the sintering and deformation of (Ti) x (TiB2)1-x composites with x = 0.05, 0.1, and 0.2, respectively, expressed in mol ratio. The temperature difference (DT) between the monitored and the temperature that the samples are exposed to was evaluated.</p><p><p>It was noticed that Ti can be sintered at relatively low temperatures. High heating rate implied that the onset temperatures of the sintering and deformation processes decreased. Increasing pressure did not affect the onset temperature but revealed that the deformation of Ti is different if the experiments are conducted within the stability region of the a -phase region of Ti or if the deformation takes place in a temperature region that covers both a-and b-phase areas, i. e. the use of high pressures implied a one step deformation process while the use of low implied that the main part of the deformation took place in the b-phase region.</p></p><p>(Ti) x (TiB2)1-x composites were prepared to full densities at 1500 °C using a holding time of 3 min and pressure of 50 MPa. During the SPS sintering the composite with x= 0.2 revealed the presence of TiB due to the reaction Ti + TiB 2 -> 2TiB while the composites with low x values did not show any formation of TiB. The formation of TiB impaired the mechanical properties. The deformation of composites was very difficult. Their deformability increased with increasing x and temperature as well as pressure. During the deformations of pre-sintered samples TiB was formed in all of the composites.</p>
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Bilgi, Eda. "Production Of Titanium Diboride." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608121/index.pdf.
Testo completoAbstract (sommario):
Titanium diboride was produced both by volume combustion synthesis (VCS) and by
mechanochemical synthesis through the reaction of TiO2, B2O3 and metallic Mg.
Reaction products were expected to be composed of TiB2 and MgO. However, side
products such as Mg2TiO4, Mg3B2O6, MgB2 and TiN were also present in the
products obtained by volume combustion synthesis. Formation of TiN could be
prevented by conducting the volume combustion synthesis under argon atmosphere.
Mg2TiO4 did not form when 40% excess Mg was used. Wet ball milling of the
products before leaching was found to be effective in removal of Mg3B2O6 during
leaching in 1M HCl. When stoichiometric starting mixtures were used, all of the side
products could be removed after wet ball milling in ethanol and leaching in 5 M HCl.
Thus, pure TiB2 was obtained with a molar yield of 30%. Pure TiB2 could also be
obtained at a molar yield of 45.6% by hot leaching of VCS products at 75oC in 5 M
HCl, omitting the wet ball milling step. By mechanochemical processing, products
containing only TiB2 and MgO were obtained after 15 hours of ball milling.
Leaching in 0.5 M HCl for 3 minutes was found to be sufficient for elimination of
MgO. Molar yield of TiB2 was 89.6%, much higher than that of TiB2 produced by volume combustion synthesis. According to scanning electron microscope analyses,
produced TiB2 had average particle size of 0.27±<br>0.08 &<br>#956<br>m.
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Severin, G. W., J. Fonslet, A. I. Jensen, and F. Zhuravlev. "Hydrolytically stable Titanium-45." Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166402.
Testo completoAbstract (sommario):
Introduction
Titanium-45, a candidate PET isotope, is under-employed largely because of the challenging aqueous chemistry of Ti(IV). The propensity for hydrolysis of Ti(IV) compounds makes radio-labeling difficult and excludes 45Ti from use in bio-conjugate chemistry. This is unfortunate because the physical characteristics are extremely desirable: 45Ti has a 3 hour half-life, a positron branching ratio of 85 %, a low Eβmax of 1.04 MeV, and negligible secondary gamma emission. In terms of isotope production, 45Ti is transmuted from naturally mono-isotopic 45Sc by low energy proton irradiation. The high cross-section and production rates on an unenriched metal foil target contribute to make 45Ti an ideal PET radionuclide.
In order to bring 45Ti to even a preclinical plat-form, the hydrolytic instability of aqueous Ti(IV) needs to be addressed. Recently, the groups of Edit Tshuva (Hebrew University of Jerusalem) and Thomas Huhn (University of Konstanz) have synthesized several stable Ti(IV) compounds based upon the salan ligand [1,2]. Additionally, these compounds have shown heightened cyto-toxicity against HT-29 (human colorectal cancer) cells, amongst others, as compared to traditional metal-based chemotherapeutics such as cisplatin.
The aim of our work has been to produce the radioactive analogue of one of these Ti(IV)-salan compounds, Ti-salan-dipic [2], which has hydro-lytic stability on the order of weeks. Not only will this allow us to shed some light on the still un-known mechanism of antiproliferative action of titanium-based chemotherapeutics, but it will also make progress toward bioconjugate 45Ti PET tracers.
In the current abstract, we present some of the methods we are using to separate 45Ti from irradiated Sc, and subsequent labeling conditions.
Material and Methods
45Ti was produced by proton irradiation of 250μm scandium foils at currents ranging from 10-20μA on a GE PETTrace. In order to increase production rate in the thin foil, an 800μm aluminum degrader was used to take the proton energy down from the nominal 16 MeV. The scandium was cooled by contact to a water-cooled silver plate.
The activated foil was dissolved in 4M HCl, dried under argon at 120 oC, and taken back up in 12M HCl. Here, four (i-iv below) different approaches to removing the Ti from the Sc and labeling were taken with varying success.
Briefly: i. 45Ti was separated on hydroxamate resin, as presented by K. Gagnon [3], only at 12M acid concentration followed by on-column radiolabeling. ii. 45Ti was extracted into 1-octanol [4], stripped with 12M HCl, and used directly for labeling from the organic phase. iii. 45Ti was trapped on a C-18 cartridge that had been pre-loaded with 1-octanol, similar to ion-pairing, and eluted with isopropanol. iv. 45Ti was extracted onto a polystyrene based 1,3 diol resin (RAPP polymers) and labeling commenced on the column.
Radiolabeling was slightly different in each condition, but in general the salan and dipic ligands were added to the 45Ti in pyridine and reacted at elevated temperature (60–100 oC) for several (10–30) minutes. Reaction progression and radiochemical purity were assessed with silica TLC in chloroform : ethyl acetate (1 : 1).
Results and Conclusion
The trap, release, and yields for the four methods listed above are shown in TABLE 1. The best result was with the 1,3 diol resin which had the added advantage of reacting on-column.
Further optimization is underway including a test of a solid supported 1,2 diol, and preclinical imaging with HT-29 xenografts.
We conclude that hydrolytically stable 45Ti com-pounds can be synthesized in high yield, and hope that this advances the radiochemistry and use of 45Ti toward more widespread applications.
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Dunn, Simon Charles. "New titanium imido complexes." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320787.
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Hollis, A. C. "Stress corrosion of titanium." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383978.
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Cooper, Robert Thomas. "η8-Permethylpentalene titanium chemistry". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:c4c3911b-1924-4e2f-a750-d07599900756.
Testo completoAbstract (sommario):
The focus of this thesis is the synthesis of organometallic complexes incorporating the η8-permethylpentalene titanium moiety (η<sup>8</sup>-Pn*Ti), their characterisation, and their reactivity with small molecules. <b>Chapter One</b> summarises the chemistry of the pentalene molecule, from its instability in the free state to the incorporation of the hydrocarbon into organometallic complexes. The chapter continues with a review of the coordination modes available to Pn and concludes with a brief discussion on the effects of permethylation of hydrocarbon ligands and the advent of permethylpentalene (Pn*). <b>Chapter Two</b> documents the improved synthesis of [Pn*TiCl(μ-Cl)]<sub>2</sub> utilising isomeric control imparted on the Pn* synthon, Pn*(SnMe<sub>3</sub>)<sub>2</sub>. This protocol permits access to a variety of methylated compounds through metathesis chemistry, of which five have been crystallographically elucidated, revealing the fold angle to be reliant on an interplay between steric and electronic factors. Mono-, bi- and trimetallic {Pn*TiMe<sub>2</sub>, [Pn*TiMe(μ-Cl)]<sub>2</sub> and [Pn*Ti(μ-Me)]<sub>2</sub>(μ-CH<sub>2</sub>), and [Pn*TiMe(μ-Me)<sub>2</sub>]<sub>2</sub>Mg respectively} species were synthesised dependent on the methylating agent employed and they displayed varying thermal stabilities, with the dimeric nature of [Pn*TiMe(μ-Cl)]<sub>2</sub> proving crucial in the formation of [Pn*Ti(μ-Cl)]<sub>2</sub>(μ-CH<sub>2</sub>). <b>Chapter Three</b> describes the incorporation of classical organometallic ligands into the Pn*Ti moiety, including the first examples of benzyl, alkyl, aryl, allyl and η<sup>1</sup>-Cp bound to a PnTi fragment. Seven complexes have been structurally characterised including the first ever crystal structure of a π-hydrocarbon bound Ti species bearing two CH<sub>2</sub><sup>t</sup>Bu groups, Pn*Ti(CH<sub>2</sub><sup>t</sup>Bu)<sub>2</sub>, and the fluxional mixed hapticity complex Pn*Ti(η<sup>5</sup>-Cp)(η<sup>1</sup>-Cp), whose η<sup>1</sup>-Cp rearranges via a 1,2-sigmatropic shift. <b>Chapter Four</b> investigates the reactivity of the monomeric dialkyls, Pn*TiR<sub>2</sub> (R = Me, CH<sub>2</sub>Ph, CH<sub>2</sub>SiMe<sub>3</sub> and CH<sub>2</sub><sup>t</sup>Bu) with CO<sub>2</sub>, CO and H<sub>2</sub>. All four compounds demonstrate “normal” insertion of the CO<sub>2</sub> moiety into both Ti-R bonds, revealing a symmetrical bidentate coordination of the RCO<sub>2</sub> units. Computational studies have highlighted two competing pathways for their reaction with CO, dependent on the concentration of CO and size of R, which results either in formation of an enediolate or a titanoxirane. The reaction with H<sub>2</sub> yields the fascinating trimeric mixed valence, [Pn*Ti(μ<sub>2</sub>-H)]<sub>3</sub>(μ<sub>3</sub>-H), the first structurally characterised example of a trimeric Ti-H species and the first to include a Ti-(μ<sub>3</sub>-H) moiety. (Pn*TiCl)<sub>2</sub>(μ-O) is formed by the action of adventitious H<sub>2</sub>O and possesses a linear Ti-O-Ti bridge with a degree of Ti-O double bond character, supported by crystallographic data and DFT calculations. <b>Chapter Five</b> discusses ethylene polymerisation studies on the monomeric dialkyl complexes Pn*TiR<sub>2</sub> (R = Me, CH<sub>2</sub>Ph, CH<sub>2</sub>SiMe<sub>3</sub> and CH<sub>2</sub><sup>t</sup>Bu) using the activators [Ph<sub>3</sub>C][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>], [PhNMe<sub>2</sub>H][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>], Al<sup>i</sup>Bu<sub>3</sub> and H<sub>2</sub>. <b>Chapter Six</b> presents full experimental procedures for all of the syntheses and reactions outlined in Chapters Two to Five. <b>Chapter Seven</b> details characterising data for all novel compounds, and crystallographic data in the form of CIF files may be found in the electronic version.
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Barbero, Bernal Laura Isabel. "Cyclic Behavior of Superelastic Nickel-Titanium and Nickel-Titanium-Chromium Shape Memory Alloys." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4937.
Testo completoAbstract (sommario):
Shape memory alloys (SMAs) are a class of alloys that display the unique ability to undergo nonlinear deformations and return to their original shape when heat is applied or the stress causing the deformation is removed. This unique shape memory characteristic is a result of a martensitic phase-change, which can be temperature induced (shape memory effect) or stress induced (superelastic effect).
In this study, the cyclical behavior of NiTi, a binary shape memory alloy, is compared to the cyclical behavior of NiTiCr, a ternary SMA. The purpose of this study is to compare the behavior of a 0.085-in. diameter NiTiCr wire with the behavior of the same size NiTi wire to determine whether ternary SMAs are more viable ways to take advantage of the unique properties of SMAs for seismic applications. The experimental results showing the superelastic behavior of these alloys under cyclical tensile loading are summarized with attention to the effects of annealing temperature, strain rate, and cyclical training on the stress-strain hysteresis, maximum recoverable strain and equivalent viscous damping.
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Bolívar, León Rafael [Verfasser]. "Synthesis of titanium powder by magnesiothermic reduction from titanium dioxide / Rafael Bolívar León." Aachen : Shaker, 2019. http://d-nb.info/1188550675/34.
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Johnson, Saccha Ellen. "Atmospheric pressure chemical vapour deposition of titanium nitride from titanium tetrachloride and ammonia." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242208.
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Molchan, Tatsiana. "Generation of porous and nanotubular anodic films on titanium and titanium-aluminium alloy." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/generation-of-porous-and-nanotubular-anodic-films-on-titanium-and-titaniumaluminium-alloy(d20970de-6692-48e6-b5f6-3456bcec5e3e).html.
Testo completoAbstract (sommario):
This project was focused on the generation of porous and nanotubular anodic films on titanium and Ti-6wt.%Al alloy, and investigation of the key factors responsible for a transition between porous and nanotubular morphologies. Advanced analytical techniques were employed for characterisation of the anodic films, in particular scanning and transmission electron microscopies, including analytical transmission electron microscopy, Raman spectroscopy, nuclear reaction analysis, Rutherford backscattering spectroscopy and atomic force microscopy. Preparation of electron transparent sections for analysis by analytical transmission electron microscopy was undertaken using the focused ion beam technique. Initially, the influence of a post-anodizing rinsing treatment, using various media, on the morphology, structure and composition of anodic films generated on titanium in 0.2 M ammonium fluoride in glycerol, containing 0 and 5 vol.% added water, was investigated. Porous anodic films were formed in an electrolyte without added water followed by rinsing with ethanol. It was revealed that the oxide-rich nanotubes are embedded in a fluoride-rich matrix, with fluoride-rich material being more extensive and oxide-rich nanotubes being thinner-walled for the anodic films generated in the electrolyte with no added water followed by rinsing with ethanol compared with those for the films formed with added water to the electrolyte and rinsed similarly. However, post-anodizing rinsing of the former films transforms the porous morphology of the films to a tubular one. The contents of titanium and fluorine were reduced in the case of anodic films with the nanotubular morphology. It was suggested that dissolution of the fluoride-rich matrix occurs during rinsing of the specimens with water, leading to the transition from porous to nanotubular morphologies and subsequent loss of titanium and fluorine. Further work was undertaken to study the effect of ageing in deionised water on the morphology, structure and composition of the anodic films. It was revealed that loss of titanium and fluorine is greater for the films generated in the electrolyte with no added water followed by rinsing with water and ethanol and ageing compared with that for the films formed in the electrolyte with 5 vol.% added water followed by rinsing with water and ethanol and ageing. Finally, the anodic films generated on the Ti-6wt.%Al alloy were investigated. Porous anodic films were formed in the electrolyte without added water followed by rinsing with ethanol whereas the films treated with water disclosed nanotubular morphology. Porous anodic films contained greater amount of fluorine than nanotubular ones. Compositional analysis revealed an increased amount of fluorine for the anodic films generated on the alloy compared with those for the films formed on titanium under all investigated conditions. The difference in film compositions may be related to the difference in composition of the substrates used for anodizing, in particular, to the presence of aluminium as alloying element in the Ti-6wt.%Al alloy.
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Zgrabik, Christine Michelle. "Wide Tunability of Magnetron Sputtered Titanium Nitride and Titanium Oxynitride for Plasmonic Applications." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493259.
Testo completoAbstract (sommario):
Transition metal nitrides have recently garnered much interest as alternative materials for robust plasmonic device architecture including potential applications in solar absorbers, photothermal medical therapy, and heat-assisted magnetic recording. Titanium nitride (TiN) is one such potential candidate. One advantage of the transition metal nitrides is that their optical properties are tunable according to the deposition conditions. The controlled achievement of tunability, however, is also a challenge. Although the formation of TiN has been the subject of numerous previous studies, a thorough analysis of the deposition parameters necessary to form metallic TiN films optimized for plasmonic applications had not been demonstrated. Similarly, such TiN films had not been subjected to detailed optical measurements which could be used in FDTD device simulations to optimize plasmonic device designs.
To be able to design, simulate and build robust and optimal device structures, in this work a systematic and thorough examination of the effect of varied substrates, temperatures, and reactive gas compositions on magnetron sputtered TiN was conducted. In addition, the effects of application of an additional substrate bias were studied. The resulting optical properties at visible to near-infrared frequencies were the focus of this thesis. The optical properties of each film were measured via spectroscopic ellipsometry with more "metallic” films demonstrating a larger negative value of the real part of the permittivity. These optical measurements were correlated with both the films’ deposition conditions and microstructural measurements including x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and transmission electron microscopy (TEM) measurements; the different deposition conditions resulted in TiN and TiOxNy films with widely tunable optical responses. By sputtering under different conditions, the value of the real part of the permittivity was tuned from small positive values, through small and moderate negative values, and finally all of the way to large negative values which are comparable to those measured in gold.
It was determined that both the chemical composition as well as the film crystallinity had a significant effect on the resulting properties with the most metallic films in general exhibiting a Ti:N ratio close to 1:1, low oxygen incorporation, more N bound as TiN rather than in oxynitride form, and better crystallinity. Increased substrate temperature in general increased the metallic character while application of a substrate bias reduced crystalline order, however also reduced oxygen incorporation and allowed for deposition of metallic TiN at room temperature. The close lattice match of TiN and MgO allowed for heteroepitaxial growth on this substrate under carefully controlled conditions.
Finally, to demonstrate the viability of the optimized TiN thin films for plasmonic applications, three benchmark plasmonic structures were simulated using the measured, optimized optical properties including a plasmonic grating coupler, infrared nanoantennas, and a nanopyramidal array. The devices were successfully fabricated and preliminary measurements show promise for plasmonic applications for example in solar conversion and photothermal medical therapy.<br>Engineering and Applied Sciences - Applied Physics
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Blank, Jonathan P. "Effect of boron additions on microstructure & mechanical properties of titanium alloys produced by the Armstrong process." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1198718818.
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Poondla, Narendra Babu. "A STUDY OF WELDED BUILT-UP BEAMS MADE FROM TITANIUM AND A TITANIUM ALLOY." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1271095999.
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Aleixo, Giorgia Taiacol. "Obtenção, caracterização microestrutural e mecanica de ligas Ti-Nb-Sn aplicadas em implantes ortopedicos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263184.
Testo completoAbstract (sommario):
Orientadores: Rubens Caram Junior, Conrado Ramos Moreira Afonso<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica<br>Made available in DSpace on 2018-08-15T14:37:29Z (GMT). No. of bitstreams: 1
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Previous issue date: 2009<br>Resumo: Este trabalho trata da preparação, processamento e caracterização microestrutral e mecânica de ligas Ti-Nb-Sn tipo ß visando a fabricação de dispositivos ortopédicos para implante. Amostras contendo Ti com teores de 25, 30 e 35% em peso de Nb e 2, 4 e 8% em peso de Sn foram preparadas por fusão a arco, homogeneizadas a 1000ºC/8 h e deformadas plasticamente por forjamento rotativo. Tais amostras foram submetidas a ensaios de resfriamento contínuo objetivando avaliar condições de obtenção de fases metaestáveis. Em seguida, amostras aquecidas a 1000ºC foram resfriadas rapidamente e submetidas a ensaios de calorimetria diferencial de varredura e de raios-X com aquecimento até médias temperaturas, o que permitiu avaliar a decomposição martensítica. Em seguida, amostras aquecidas no campo ß foram resfriadas ao ar, o que resultou em microestruturas com a fase a precipitada na matriz ß. Tais amostras foram caracterizadas no tocante à microestrutura via microscopia ótica, eletrônica de varredura e de transmissão e difração de raios X, enquanto que o comportamento mecânico foi avaliado por meio de testes de dureza Vickers, de medidas de módulo de elasticidade usando técnicas acústicas, ensaios de tração e ensaios de fadiga. Os resultados obtidos indicam que a decomposição da martensita resulta nas fases ß, ? e finalmente, a e também, que a fase ? atua como substrato na nucleação da fase a. O comportamento mecânico das amostras depende diretamente das fases presentes na microestrutura, bem como de suas frações volumétricas. Constatou-se também que o módulo de elasticidade, a dureza e o limite de resistência à tração de amostras resfriadas ao ar exibem valores superiores aos valores obtidos com as amostras resfriadas rapidamente, enquanto que a ductilidade se reduz. Finalmente, observou-se que o limite de fadiga de amostras resfriadas ao ar é máximo para baixos teores de Nb e se reduz com a adição de Sn<br>Abstract: This work deals with preparation, processing and microstructural and mechanical characterization of ß type Ti-Nb-Sn alloys aiming the manufacturing of orthopedic devices for implants. Ti samples containing Nb at levels of 25, 30 and 35 wt % and Sn at levels of 2, 4 and 8 wt % were prepared by arc melting, homogenized at 1000ºC/8 h and plastically deformed by swaging. These samples were submitted to continuous cooling experiments to evaluate conditions for obtaining metastable phase. Then, samples heated to 1000ºC were rapidly cooled and analyzed by using differential scanning calorimetry and X-ray diffraction at medium temperatures, which allowed the evaluation of martensite decomposition. Next, samples in the ß field were air-cooled, which resulted in microstructures with a phase precipitated into ß matrix. These samples were characterized concerning the microstructure by applying optical, scanning electron and transmission electron microscopies and X-ray diffraction, while the mechanical behavior was evaluated by Vickers hardness test, elastic modulus measurement using acoustic techniques, tensile and fatigue tests. The results obtained indicate that martensite decomposition results in ß, ? and finally a phases. It was also found that ? phase acts as substrate for a phase nucleation. The sample mechanical behavior directly depends on the phases present in the microstructure, as well as their volumetric fraction. It was also observed that elastic modulus, hardness and tensile strength of air cooled samples show higher values than those of rapidly quenched samples, while ductility decreases. Finally, it was observed that fatigue resistance of air cooled samples is higher for low Nb content alloys, however, it decreases with Sn addition<br>Doutorado<br>Materiais e Processos de Fabricação<br>Doutor em Engenharia Mecânica
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Cumba, Loanda Raquel [UNESP]. "Preparação e aplicação eletroanalítica de complexos metálicos formados a partir de titânio (IV) e ácido fosfórico seguindo uma nova rota de síntese." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/97899.
Testo completoAbstract (sommario):
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cumba_lr_me_ilha.pdf: 1172695 bytes, checksum: 022bcc613710f630671a10681e48bedb (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O presente trabalho descreve a preparação, caracterização e aplicação eletroanalítica de um compósito formado por Titânio fosfatado modificado com metais de transição (Ag1+, Co2+ e Ni2+) e hexacianoferrato de potássio. A primeira etapa consistiu em reagir o isopropóxido de titânio (IV) com H3PO4, sendo que o material obtido foi descrito como TiP. Em uma segunda etapa reagiu-se o TiP com íons metálicos, originando TiPM (M = Ag1+, Co2+ e Ni2+). Algumas técnicas espectroscópicas como espectroscopia vibracional (FT-IR), Difração de Raios X (DRX), Espectroscopia na região do ultravioleta visível (UV-Vis por Reflectância difusa)e Voltametria cíclica foram utilizadas na caracterização do TiP e do TiPMH. Os espectros na região do Infravermelho dos materiais supracitados exibiram freqüências em 2112 cm-1 para o TiPAgH, 2136 cm-1 para o TiPCoH e um a 2168 cm-1 e outro a 2099 cm-1 para o TiPNiH, atribuídas ao estiramento (C≡N) característico do hexacianoferratos de prata, cobalto e níquel. Através dos difratogramas pode se verificar a diferença de cristalinidade dos complexos binucleares formados. A Espectroscopia na região do ultravioleta visível (UV-Vis por Reflectância difusa)das espécies suportadas, TiPCoH, após deconvolução espectral, exibiu claramente duas absorções com comprimento de onda máximo (max) em 437 e 504 nm para o TiPCoH, em 421 a 461 nm para o TiPAgH e em em 423 e 433 nm para o TiPNiH. Por fim, efetuou-se um estudo eletrocatalítico de substâncias de interesse biológico, utilizando um eletrodo de pasta de grafite modificado com TiPMH, após um rigoroso estudo sobre o comportamento voltamétrico dos mesmos. O eletrodo de pasta de grafite contendo o TiPAgH exibiu um par redox com potencial médio (E’) de: (E’) = 0,77V vs Ag/AgCl atribuído ao processo...<br>The present work describes the preparation, characterization and electroanalytical application of a composite consisting of titanium phosphate modified with transition metals (Ag1+, Co2+ and Ni2+) and potassium hexacyanoferrate. The first step consisted in reacting the titanium isopropoxide (IV) with H3PO4, being that the material obtained was described as TiP. In a second step if the TiP reacted with metal ions, giving TiPM (M = Ag1+, Co2+ and Ni2+). Some techniques such as vibrational spectroscopy (FT-IR), X-ray diffraction (XRD), Diffuse Reflectance and cyclic voltammetry were used to characterize the TiP and TiPMH. The spectra in the region of Infrared of materials abovementioned exhibited frequencies in 2112 cm -1 for TiPAgH, 2136 cm-1 for TiPCoH and one to 2168 cm-1 and another to 2099 cm-1 for TiPNiH, attributed to stretching (C ≡ N) characteristic of hexacyanoferrates of silver, cobalt and nickel. Through the diffractograms can verify the difference of crystallinity of the complexes binuclear formed. The diffuse reflectance of species supported after spectral deconvolution, clearly showed two absorptions with peak wavelength ( max) at 437 and 504 nm for TiPCoH at 421 and 461 nm for TiPAgH and in 423 and 433 nm for the TiPNiH. Finally, we performed an electrocatalytic study of substances of biological interest, using a carbon paste electrode modified with TiPMH, after a rigorous study on the voltammetric behavior of the same. The carbon paste electrode containing TiPAgH exhibited a redox couple with average potential (E') of (E') = 0.77 V vs Ag/AgCl(s) redox process attributed to FeII(CN)6 / FeIII(CN)6 in presence of silver. The carbon paste electrode modified with TiPAgH showed electrocatalytic activity for three substances of biological interest... (Complete abstract click electronic access below)
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Capellato, Patricia [UNESP]. "Caracterização da superfície da liga Ti-30Ta após crescimento de nanotubos." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/103758.
Testo completoAbstract (sommario):
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capellato_p_dr_guara.pdf: 1337923 bytes, checksum: 3edc5b93305051c3258b073892d9965d (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Titânio CP e a liga Ti6Al4V são amplamente empregados na fabricação de componentes para aplicações biomédicas. No entanto, estes materiais podem causar problemas de saúde em função da liberação de íons metálicos citotóxicos e reabsorção do osso adjacente devido a grande diferença entre o modulo de elasticidade do material e osso. Esses fatores têm levado ao desenvolvimento de novas ligas de titânio e também de novas técnicas de modificação de superfície. Amostras da liga experimental Ti-30Ta na forma de discos com 13 mm de diâmetro e 3 mm de espessura foram empregadas nesse estudo. O processo de anodização foi realizado sob tensão de 15V, 25V e 35V e tempos de 20 e 40 min em eletrólito formado por HF/H2SO4 com adição de dimetil sulfóxido (DMSO). A calcinação das amostras foi realizada a 530ºC durante 3 h. As superfícies foram avaliadas empregando-se MEV-FEG, EDS e a molhabilidade avaliada com ângulo de contato. Todas as condições avaliadas apresentam superfície hidrofílica. Nanotubos de Ti-30Ta foram obtidos na condição 35V-40 mim apresentado 100 nm de comprimento e 80-100 nm de diâmetro. A biocompatibilidade da liga Ti-30Ta com nanotubos foi avaliada após 24 e 72 horas de cultura celular com fibroblastos dérmicos humanos (HDF, neonatal). A adesão e proliferação celular, viabilidade, organização do citoesqueleto e morfologia celular foram investigadas por meio de imagens de microscópio de fluorescência, ensaios bioquímicos e MEV-FEG. Análise celular demonstrou aumento significativo na adesão e proliferação celular, viavilidade, alongamento e produção de matriz extracelular de fibroblastos na superfície da liga Ti-30Ta com nanotubos após 72 horas de cultura celular...<br>In the last years, titanium and theirs alloys have been used in dental applications due their excellent properties such as corrosion resistance and biocompatibility. However, these materials are considered bioinerts and due to your poor physiological integration that may result in fibrous encapsulation and further biomaterial rejection. Ti-30Ta alloys, for use in biomedical applications are the subject of this research. The aim is to discover optimal alloy proportions for tissue-like mechanical properties and improved biocompatibility. Of the alloys tested, 30% Ta with Ti exhibits favorable properties including a low elastic modulus, improved strain-resistance and increased elongation to failure. Recent studies have identified strong correlations between anodized metals and the production of highly biomimetic nanoscale topographies. These surfaces provide an interface of enhanced biocompatibility that exhibits a high degree of oxidation and surface energy. In this study, the mechanical substrate and topographical surface properties of anodized Ti-30Ta alloy were investigated using scanning electron microscopy (SEM), energydispersive spectroscopy (EDS) and contact angle measurement. The anodization process was performed in an electrolyte solution containing HF (48%) and H2SO4 (98%) in the volumetric ratios 1:9 with the addition of 5% dimethyl sulfóxido (DMSO) at 15V, 25V and 35V for 20 and 40 min, producing a nanotube architecture when anodized at 35V for 40 min. Human dermal fibroblasts (HDF, neonatal) were utilized to evaluate the biocompatibility of Ti-30Ta nanotubes after 24 and 72 hours of culture. Cellular adhesion, proliferation, viability, cytoskeletal organization and morphology were investigated using fluorescence microscope imaging, biochemical assay and SEM imaging respectively... (Complete abstract click eletronic access below)
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Rigolin, Maria Silvia Mauricio [UNESP]. "Influência de características físicas e química dos materiais de abutments de implantes em zircônia e titânio na adesão e viabilidade de células epiteliais gengivaiS OBA-9." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/110832.
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000796267.pdf: 2331595 bytes, checksum: a54fbece3e4646af27b186ebe1b5047b (MD5)<br>Dada à necessidade de uma efetiva barreira tecidual precoce ao redor dos implantes osseointegrados, o presente estudo avaliou, in vitro, a influência das características físicas e químicas de materiais simulando superfícies de abutments de implantes em titânio (T) e zircônia (ZrO2) na adesão de células epiteliais gengivais OBA-9. Para este estudo foram utilizados espécimes em forma de discos (n=13) de titânio e zircônia, e como controles positivo e negativo, discos de esmalte bovino (EB) e lamínulas de vidro (LV), respectivamente. Foram avaliadas previamente a adesão celular a rugosidade superficial (Ra), energia livre de superfície (ELS) e os elementos químicos presentes na superfície identificados por meio de Espectrômetro de raios-X por Dispersão de Energia em Microscópio Eletrônico de Varredura (MEV). Após a adesão celular em 1 e 24 horas, foram avaliadas a viabilidade celular por meio do MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide); e a morfologia das células aderidas sobre as superfícies por meio de MEV. Os dados de viabilidade celular foram avaliados estatisticamente pelo teste de ANOVA a dois critérios fixos (“material” e “período de análise”), enquanto os dados de ELS foram submetidos aos testes de Kruskal-Wallis e Mann-Whitney, considerando um nível de significância de 5%. A superfície de T obteve o maior valor de ELS com 6,2N/m, seguida pela ZrO2 com 5,8N/m, LV com 4,9N/m, e com o menor valor o EB com 4,7N/m. Foi observado que os fatores material (p=0,336) e período de análise (p=0,400) não apresentaram efeito sobre os dados de viabilidade celular, assim como a interação entre eles (material*período de análise, p=0,559). A análise da morfologia celular mostrou que as células aderidas às superfícies de T e ZrO2 apresentaram espraiamento semelhante, sendo este maior quando comparado as superfícies de EB e LV. Concluiu-se que não houve diferença entre a adesão...<br>Given the need for effective early mucosal barrier around dental implants, the present study evaluated, in vitro, the influence of physical and chemical characteristics of materials simulating abutments implants surfaces in titanium (T) and zirconium (ZrO2) on gingival epithelial cells OBA-9 adhesion. For this study, disks-shaped samples (n=13) of titanium and zirconium were tested, and as positive and negative control groups, bovine enamel disks (BE), and glass coverslips (GCS), respectively. Previously the cellular adhesion surface roughness (Ra), surface free energy (SFE) and the chemical composition of specimens by X-ray Spectrometer Dispersive Energy in Scanning Electron Microscope (SEM) were evaluated. After the periods of cellular adhesion, 1 and 24 hours, the cellular viability was evaluated by MTT Assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and the morphology of the epithelial cells adhered to the surfaces was analyzed using the SEM. The data of cell viability were statistically evaluated by two-way ANOVA (Material and period of analysis), while the SFE data were submitted to Kruskal-Wallis and Mann-Whitney tests, considering a significance level of 5%. The T specimens showed the highest values of SFE (6.2 N/m), followed by ZrO2 (5.8 N/m), GCS (4.9 N/m), and BE (4.7 N/m). It was observed that the factors material (p = 0.336) and periods of analysis (p = 0.400) showed no effect on cell viability data, as well as the interaction between them (material* period of analysis, p = 0.559). The analysis of cell morphology showed that cells adhered to the T and ZrO2 surfaces presented similar spreading, which was higher compared to the BE and GCS surfaces. It was concluded that there was no difference between the cellular adhesion to different materials for implant abutments, T and ZrO2, in evaluated periods. However, cell spreading was qualitatively higher in rougher surfaces and greater titanium and zirconia...
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Souza, Jéssica Porto [UNESP]. "Estudo comparativo de filmes de corantes fenotiazínicos na superfície de eletrodo de carbono vítreo e adsorvidos em titânio fosfatado e suas aplicações eletroanalíticas." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/127943.
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000847760.pdf: 3041903 bytes, checksum: 3d088ce3b9a41318446f3ae996281823 (MD5)<br>O presente trabalho descreve a preparação, caracterização e aplicação eletroanalítica de um compósito formado por titânio fosfatado modificado com os corantes da classe das fenotiazinas, a saber: azul de metileno (TiPAM), azul de orto toluidina (TiPAO) e azure A (TiPAA). Os compósitos foram caracterizados por técnicas espectroscópicas tais como: espectroscopia vibracional (FTIR), microoscopia eletrônica de varredura (MEV) e voltametria cíclica. Os espectros na região do Infravermelho dos compósitos apresentaram absorções características dos TiP nas regiões de 1012 a 1022 cm -1 atribuídas ao estiramento Ʋ (P=O) e 621 a 751 cm -1 atribuídas as ligações O-Ti-O, apresentaram também absorções características dos corantes fenotiazínicos nas regiões de 1478 a 1484 cm -1 atribuídas aos anéis aromáticos presentes na estrutura dos corantes e vibrações nas régios de 1384 a 1396 cm -1 equivalentes as ligações C-N. A microscopia eletrônica de varredura dos materiais revelou a presença de nanopartículas esféricas, com tamanhos que variaram de 230 a 752 nm. Efetuou-se estudos eletrocatalíticos de substâncias de interesse biológico, utilizando um eletrodo de pasta de grafite modificado com TiPAM, TiPAO e TiPAA, após um rigoroso estudo sobre o comportamento voltamétrico dos mesmos. Ambos exibiram dois pares redox bem definidos, processo I e II, atribuídos ao processo de eletropolimerização. O eletrodo de pasta de grafite modificado com TiPAM apresentou eletroatividade para o sulfito e os demais ao ácido ascórbico. Adicionalmente efetuou-se um estudo eletrocatalítico utilizando os filmes dos corantes utilizados na superfície do eletrodo de carbono vítreo. Os voltamogramas cíclicos apresentaram dois pares redox bem definidos, atribuídos a diferentes espécies geradas na eletropolimerização. Os eletrodos apresentaram atividade eletrocatalítica para o ácido ascórbico<br>This paper describes the preparation, characterization and electroanalytical application of a composite consisting of titanium phosphate modified with dyes of phenothiazine class, as follows: methylene blue (TiPAM), ortho toluidine blue (TiPAO) and azure A (TiPAA). The composites were characterized by spectroscopic techniques such as vibrational spectroscopy, scanning electron microoscopia (SEM) and cyclic voltammetry. The spectra in the infrared region of the composite showed characteristic absorptions of TiP the regions 1012-1022 cm -1 assigned to Ʋ (P = O) and 621-751 cm -1 assigned links O-Ti-O, also showed absorptions characteristics of phenothiazines dyes in the regions from 1478 to 1484 cm -1 attributed to aromatic rings present in the structure colors and vibrations in regal 1384-1396 cm -1 equivalent of the C-N bonds. The scanning electron microscopy of materials revealed the presence of spherical nanoparticles with sizes ranging from 230 to 752 nm. Made up electrocatalytic studies of biologically relevant substances, using a carbon paste electrode modified with TiPAM, TiPAO and TiPAA, after a rigorous study on the voltammetric behavior of the same. Both showed two well-defined redox couples, I and process II, assigned to electropolymerization process. The carbon paste electrode modified with TiPAM presented electroactivity for sulphite and other ascorbic acid. Additionally made up an electrocatalytic study using the dyes of the films used on the surface of the glassy carbon electrode. The cyclic voltammetry showed two well-defined redox pairs assigned to different species generated in electropolymerization. The electrodes showed electrocatalytic activity for ascorbic acid. And by comparing the different electrodes it was observed that the graphite paste-modified electrodes TiPAM, and TiPAO TiPAA was obtained best results
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McCormick, John. "Chemistry of titanium dioxide nanoparticles." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 10.93 Mb., 224 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220706.
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Odelros, Stina. "Tool wear in titanium machining." Thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-176944.
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The present work was performed at AB Sandvik Coromant as a part in improving the knowledge and understanding about wear of uncoated WC/Co cutting tools during turning of titanium alloy Ti-6Al-4V. When machining titanium alloys, or any other material, wear of the cutting tools has a huge impact on the ability to shape the material as well as the manufacturing cost of the finished product. Due to the low thermal conductivity of titanium, high cutting temperatures will occur in narrow regions near the cutting edge during machining. This will result in high reaction and diffusion rates, resulting in high cutting tool wear rates. To be able to improve titanium machining, better knowledge and understanding about wear during these tough conditions are needed. Wear tests were performed during orthogonal turning of titanium alloy and the cutting tool inserts were analysed by SEM, EDS and optical imaging in Alicona InfiniteFocus. Simulations in AdvantEdge provided calculated values for cutting temperatures, cutting forces and contact stresses for the same conditions as used during wear tests. It was found that turning titanium alloy with WC/Co cutting tools at cutting speeds 30-60 m/min causes chamfering of the cutting tool edge and adhesion of a build-up layer (BUL) of workpiece material on top of the rake face wear land. The wear rate for these low cutting speeds was found to be almost unchanging during cutting times up to 3 minutes. During cutting speeds of 90-115 m/min, crater wear was found to be the dominating wear mechanism and the wear rate was found to have a linear dependence of cutting speed. An Arrhenius-type temperature dependent wear mechanism was found for high cutting speeds, between 90 and 115 m/min.
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Dewan, Mohammad Ashikur Rahman Materials Science & Engineering Faculty of Science UNSW. "Carbothermal synthesis of titanium oxycarbide." Awarded By:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/44511.
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The aim of the project was to establish the rate and mechanisms of solid stage reduction of titania and ilmenite ores. The project examined carbothermal reduction of titania and various types of ilmenite ores in argon, helium, hydrogen, and their mixtures. Effect of CO in the gas atmosphere on reduction behavior of titania and primary ilmenite ore was also studied. Isothermal and non-isothermal reduction experiments were conducted in a fixed bed reactor in the high temperature furnace in the temperature range up to 1500oC. The off-gas composition in the reduction process was monitored by a CO/CO2/CH4 infrared analyser. The extent of reduction was calculated using data on gas composition and LECO oxygen analysis. Phase composition and morphology of reduced samples were studied using XRD, SEM and optical microscopy. The major findings of this project are as follows: The reduction of titania to titanium oxycarbide occurred in the following sequence: TiO2 → Ti5O9 → Ti4O7 → Ti3O5 → Ti2O3 → (TiO-TiC) solid solution. Carbothermal reduction of ilmenite concentrates proceeded in two main stages. In the first stage pseudorutile and ilmenite were reduced to metallic iron and titania. Second stage involved the reduction of titania to titanium oxycarbide. Rate and degree of reduction of titania and ilmenite concentrates increased with increasing temperature. Reduction rate of titania and ilmenite concentrates was faster in hydrogen than in helium and argon. The difference in the reduction behavior in helium and argon was insignificant; reduction rate of ilmenite was slightly faster in helium than in argon. High rate of reduction of titania and ilmenite in hydrogen was attributed to formation of methane which facilitated mass transfer of carbon from graphite to oxide. Hydrogen was also directly involved in reduction of titania and ilmenite concentrates; hydrogen reduced pseudorutile to iron and titania. Titania was further reduced to titanium oxycarbide by carbon through methane. Increased gas flow rate slightly improved the reduction rate in hydrogen and suppressed the reduction in inert gases. Addition of CO to hydrogen and inert gases above 3 vol% suppressed the reduction process.
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Noël, James J. "The electrochemistry of titanium corrosion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0028/NQ51663.pdf.
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Matykina, Endzhe. "Plasma electrolytic oxidation of titanium." Thesis, University of Manchester, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548672.
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Harris, R. "Atomistic simulations of titanium carbide." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603742.
Testo completoAbstract (sommario):
This thesis comprises three related studies of titanium carbide, a refractory material, using atomistic simulations based on the Tight Binding model of cohesion. The first study is a detailed critique of a recently published Tight Binding parameterisation for titanium carbide. In addition to correcting a large number of issues in the original source, the optimisation and suitability of the model were also investigated. In the second study, the same Tight Binding model was applied to the determination of the order structure of TiC<SUB>0.5</SUB>. Owing to a peculiarity of this structure, its unique determination has not been possible using conventional (powder diffraction) techniques. Thus, at least two symmetries have been assigned to TiC<SUB>0.5</SUB> based on experimental work; the results of this thesis allow a distinction to be made on the basis of quantum mechanical calculations. The third and final study is concerned with the deformation processes of TiC<SUB>2</SUB> which displays certain properties that distinguish it from other materials with the same (NaCl) structure. On the basis of a number of simulations, a model for the deformation behaviour is introduced. This model is used to explain the preferred slip system at low temperatures, the origin of the brittle to ductile transition, the expected dislocation dissociation reactions and the origin of the observed change in apparent activation energy of shear stress.
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Unosson, Erik. "Antibacterial Strategies for Titanium Biomaterials." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-249181.
Testo completoAbstract (sommario):
Titanium and titanium based alloys are widely used in dentistry and orthopedics to replace hard tissue and to mend broken bones. It has become a material of choice due to its low density, high strength, good biocompatibility and its capacity to integrate closely with the bone. Today, modern materials and surgical techniques can enable patients to live longer, and aid in maintaining or regaining mobility for a more fulfilling life. There are, however, instances where implants fail, and one of the primary causes for implant failure is infection. This thesis deals with two possible ways of reducing or eliminating implant associated infections; TiO2 photocatalysis, where a surface can become antibacterial upon irradiation with UV light; and incorporation of silver, where a subsequent release of silver metal ions result in an antibacterial effect. For the TiO2 photocatalysis strategy, a simple and cost effective chemical oxidation technique, using hydrogen peroxide (H2O2) and water, was used to create an active TiO2 surface on titanium substrates. This surface was shown to effectively degrade an organic model substance (rhodamine B) by generating reactive oxygen species (ROS) under UV illumination. However, it was shown that Ti-peroxy radical species remaining in the surface after the H2O2-oxidation process, rather than generation of ROS from a heterogeneous photocatalytic process, was responsible for the effect. This discovery was further exploited in a TiO2/H2O2/UV system, which demonstrated synergy effects in both rhodamine B degradation tests and in antibacterial assays. For the silver ion release strategy, a combinatorial materials science approach was employed. Binary Ag-Ti oxide gradients were co-deposited in a reactive (O2) environment using a custom built physical vapor deposition system, and evaluated for antibacterial properties. The approach enabled synthesis and composition-structure-property evaluation unlikely to have been achieved by traditional means, and the gradient coatings demonstrated antibacterial properties against both S. aureus and S. epidermidis according to silver ion release. The release was shown to depend more on structural features, such as surface area, crystallinity and oxidation state, than on composition. Ag-Ti oxide gradients were also evaluated under UV illumination, as Ag deposits on crystalline TiO2 can enhance photocatalytic properties. In this work, however, the TiO2 was amorphous and UV illumination caused a slight reduction in the antibacterial effect of silver ions. This was attributed to a UV-induced SOS response in the S. epidermidis bacteria. The results of this thesis demonstrate that both TiO2 photocatalysis, or UV induced activation of Ti-peroxy radical species, as well as incorporation of silver are viable antibacterial strategies for titanium biomaterials. However, their clinical applications are still pending risk-benefit analyses of potential adverse host tissue responses.
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Harrison, Robert William. "Reduction of titanium dioxide photoactivity." Thesis, University of Newcastle Upon Tyne, 2006. http://hdl.handle.net/10443/856.
Testo completoAbstract (sommario):
Titanium dioxide, "titania" is used for a wide range of everyday applications, such as in sunblocks, paints, paper, and some plastics. For these uses it is necessary to reduce the photoactivity of the titania for either product quality or consumer safety. Titanium dioxide also finds application in the field of photocatalysis for pollution abatement and in this instance a high photoactivity is desirable. This thesis describes the development and characterisation of two main strategies intended to reduce titania photoactivity: the addition of iron dopants to suppress the number of surface radicals (Chapters 3 and 4), and the addition of an organic coating to the titania to scavenge the radicals (Chapters 5 and 6). The titania was iron doped in two ways, either only on the surface, or in the lattice and on the surface (shown by Electron Paramagnetic Resonance "EPW' spectra). The effect of several novel organic coatings on the photoactivity was tested: a phosphate, an organophosphate based coating and an organosilane. Two types of titanium dioxide were modified, a rutile sample used in commercial sunblocks and Degussa P25, a titania commonly used in research. The efficiencies of these strategies were tested by several methods to determine the effect of solution medium on the photoactivity. A new technique of 2-nitrophenol degradation was developed to measured photoactivity in aqueous solutions and compared with the well characterised technique of 2-propanol oxidation. In addition, a test based on salicylic acid degradation was developed and shown to measure the photoactivity by direct hole oxidation. Infra red spectroscopy and surface area determination were used to analyse how the coatings formed on the titania surface. IR spectra show that the headgroups bond to the surface and so the coatings are hydrophobic. Careful analysis showed that organosilanes form on the surface as crosslinked polymers. Lastly, work on 4-nitrophenol degradation carried out under my guidance complements earlier work on 2-nitrophenol degradation to show that UV absorption by the solution affects the measured kinetics of photocatalytic degradation.