Uma das grandes aplicações dos sensores magnetoelásticos está relacionada aos sistemas antifurto. Devido ao seu excelente desempenho e natureza passiva sem fio, também têm sido amplamente utilizados no sensoriamento ambiental em resposta às mudanças de temperatura, pressão atmosférica, velocidade de fluxo do fluido através da superfície do sensor, densidade e viscosidade de líquidos e variação de massa. O presente trabalho investiga a utilização de fitas magnetoelásticas, tais como Metglas®2826MB3, para estudar o comportamento de secagem de materiais cerâmicos. Duas argilas extraídas da região do Vale do Caí, principal produtor de materias cerâmicos para a construção civil, foram analisadas. Suspensões de argila foram preparadas e sua caracterização foi realizada por meio de técnicas tradicionais que considerou a cinética de secagem, a retração e o comportamento das trincas de acordo com a massa úmida do material depositado em um molde de alumínio. Posteriormente as suspensões foram depositadas sobre a superfície da fita sensora com auxílio de um dispositivo doctor blade. Aplicando um campo magnético variável, foi possível determinar a frequência de ressonância experimental do sensor. Essa frequência é inversamente proporcional ao comprimento da fita e dependente das propriedades físicas dos materiais. Um modelo matemático foi utilizado para relacionar a frequência de ressonância com as propriedades elásticas da cobertura da fita. Além das propriedades físicas dos materiais também foi incluído ao modelo, a dependência do módulo de elasticidade da fita em campo magnético, conhecido como efeito E. A tensão desenvolvida durante o processo de secagem pode gerar trincas e deformações no material quando não dissipadas. Essa tensão contribui para a anisotropia magnética e é introduzida no problema através do efeito E. A técnica do cantilever foi utilizada para verificar a presença de tensões durante a secagem. Medindo a deflexão do substrato é possível determinar a tensão gerada pela suspensão. As curvas da frequência de ressonância em função do tempo mostram várias regiões distintas. Na região que distingue os dois principais estágios de secagem da suspensão, caracterizada pela taxa de secagem que diminui aceleradamente, a medida da frequência se mostrou bastante sensível à presença de tensões. Portanto, as estruturas observadas nas curvas experimentais de frequência em função do tempo puderam ser reproduzidas pelo modelo, utilizando a distribuição de tensões experimentais e as propriedades elásticas do sensor e da suspensão de argila. Esse resultado promissor sugere que as tensões desenvolvidas durante a secagem de materiais cerâmicos poderiam ser determinadas por medidas da frequência de ressonância dos sensores. / An important application of magnetoelastic sensors is in antitheft systems. Because of their excellent performance and their passive wireless nature, they have also been extensively used in environmental sensing of changes in temperature, atmospheric pressure, flow speed of fluid over the sensor surface, density and viscosity of liquids and mass change. The present work investigates the use of magnetoelastic sensors based on Metglas®2826MB3 to study the drying behavior of ceramic materials. Two clays from the Vale do Caí region, the main producer of ceramic materials for the construction industry, were analyzed. Aqueous clay suspensions were prepared and their characterization was performed using traditional techniques that considered the drying kinetics, shrinkage and cracking behavior as a function of the wet weight of the material deposited into an aluminum mold. Subsequently, the suspensions were deposited on the sensor tape surface with a doctor blade device. Applying a variable magnetic field, it was possible to determine the experimental resonance frequency of the sensor. This frequency is inversely proportional to the ribbon length and dependent upon the physical properties of the materials. A mathematical model was used to correlate the resonance frequency with the elastic properties of the coating. Besides the physical properties of the materials, also included in model was the dependence of the tape's elastic modulus on magnetic field, known as the E effect. The stress developed during the drying process may cause cracks and deformations in the material when it is not dissipated. This stress contributes to the magnetic anisotropy which is introduced into the problem through the E effect. The cantilever technique was used to determine the presence of tensions during drying. Measuring the deflection of the substrate, it is possible to determine the stress generated by the suspension. The curves of resonance frequency versus time show several distinct regions. For the region that separates the two main rying stages of the suspension, the frequency measurement proved to be very sensitive to the presence of tension. Therefore, the structures observed in the experimental curves of frequency versus time could be modeled using the experimental distribution of stress and the elastic properties of the sensor and clay suspension. This promising result suggests that the tensions developed during the drying of ceramic materials could be determined by measurements of the resonance frequency of the sensors.

Esta dissertação associa a cerâmica às novas tecnologias do computador objetivando a criação de um CD-ROM híbrido. Trabalho que se realiza na construção de uma grande rede tramada com a poética da terra, dos devaneios da matéria, da massa e do fogo, do laborioso jogo do fazer com as mãos, com a poética do virtual, da extensão do corpo, do caminho labiríntico que se desdobra em muitas possibilidades no instante de um clicar eletrônico. Ao longo do desenvolvimento deste CD-ROM, imagens poéticas estarão entrelaçadas às informações e conhecimento científico sobre o assunto. A partir do conceito de trama é desenvolvida, com registros fotográficos e em vídeos, uma pesquisa pessoal com o material cerâmico em ateliê. Imagens destes trabalhos são utilizadas ao longo da construção do objeto CD-ROM assim como a de outras produções. Neste CD apresentam-se alguns profissionais brasileiros, que utilizam a cerâmica como suporte para sua expressão plástica, seus trabalhos, além de diversas técnicas e processos deste fazer. Todo o conteúdo informativo poderá ser acessado e enriquecido através da interatividade possibilitada pela hipermídia. Trata-se, portanto, de um trabalho que enfoca o individual e o coletivo. Utilizou-se para este desenvolvimento conceitos da área da comunicação e informática, tais como multimídia, hipermídia, hipertexto, interatividade, labirinto e rizoma, entre outros. / This issues associated with ceramic to the new technologies of computer and its goals on the creation of a hybrid CD-ROM. This work takes place in the construction of a great net schemed with the poetic of the earth, of the fantasy of the matter, of the mass and of the fire, the laborious game of doing with hands, with poetic of the virtual, of the extension of the body, of the labyrinth road that is unfolded in a lot of possibility in the moment of electronic clicks. Along the development of this CD-ROM, poetic of images will be interlaced to the information and scientific knowledge on the subject. It starts from the plot concept and it is developed with photographic registration and video, also with a personal research with the ceramic material in atelier. Image of these works have been used along the construction of this CD-ROM, as well as one of another productions. In this CD there are some Brazilians professionals that use the ceramic as support for its plastic expression in their works, besides several techniques and processes of this. The whole informative content can be accessed and enriched, through the integrate possibility for the hypermedia. It is, therefore, a work that focuses the individual and the collectively. It was used for this development several concepts of the area of the communication and computer science as multimedia, hypermedia, hypertext, interactive, labyrinth and rhizome among others.

Objetivo: Avaliar a influência de diferentes tratamentos de superfície da zircônia na rugosidade superficial e na resistência de união utilizando diferentes agentes de cimentação, pré e pós-ciclagem térmica, bem como analisar a superfície de fratura. Metodologia: Foram elaborados três artigos científicos. No Capítulo 1, apresentou-se um estudo de revisão da literatura a respeito dos métodos de tratamento de superfície e os diferentes tipos de cimentos indicados para proporcionar união adesiva entre a zircônia e materiais resinosos. No Capítulo idade da superfície modificada e a resistência da união entre cerâmica e material resinoso. Os tratamentos de superfície analisados foram: jateamento com partículas de Al2O3 de 50μm, aplicação de primer contendo MDP, silicatização e silicatização associado a aplicação de primer contendo MDP, além da associação de dois tipos de cimentos resinosos, cimento resinoso modificado com monômeros fosfatados e cimento resinoso autoadesivo. Foi utilizado o teste de rugosidade e de microcisalhamento para verificar a alteração de superfície e a força de adesão proporcionada pelos grupos experimentais seguidas de análise do modo de falha para verificar as características da interface adesiva. No capítulo 3 foi realizado o mesmo delineamento do Capítulo 2, entretanto, foi associado o processo de ciclagem térmica para verificação do comportamento dos diferentes tratamentos de superfícies e materiais cimentantes, com intuito de simular parcialmente condições clínicas. Conclusões: Ambos os cimentos utilizados podem ser indicados para a cimentação adesiva da cerâmica a base de zircônia. Em relação aos cimentos resinosos modificados o tratamentos de superfície apresenta-se indispensável para possibilitar melhora na resistência de união. O tratamento com a cobertura de sílica associado ou não ao primer apresentou-se com melhores resultados. Em relação aos cimentos autoadesivos o tratamento de superfície não teve grande influência na resistência de união, porém melhores resultados foram obtidos nas superfícies tratadas com a cobertura de sílica. Após a ciclagem térmica foi observado que o cimento autoadesivo apresentou melhores valores de força de adesão em comparação ao cimento resinoso modificado, independente do tratamento de superfície realizado. / Objective: To evaluate the influence of different surface treatments of zirconia in surface roughness and bond strength using different cementing agents, before and after thermal cycling as well as analyze the fracture surface. Methods: We developed three papers. In Chapter 1, presented a study of the review of the literature on the methods of surface treatment and different types of cements indicated for providing bonding between zirconia and resin materials. In Chapter 2, an experiment was designed to evaluate the influence of different types of surface treatment of ceramic and cement types on the surface roughness of the modified surface and the bond strength between compositive material and ceramics. The w yz w h A O3 50μ applying primer containing MDP, and silicatization associated with applying primer containing MDP. A resin cement modified with phosphate monomers and self-adhesive resin cement were also analyzed. Roughness and microshear test was used to verify the change of surface, and the adhesion strength provided by the experimental groups followed by analysis of the way to check the characteristics of the adhesive interface. The analyzed results were submitted to statistical analysis. In chapter 3 was used the same design done in Chapter 2, however, thermal cycling process was associated to verify the behavior of different surface treatments and materials with the aim of partially simulate clinical conditions. Conclusions: Both cements used might be indicated for the adhesive cementation of zirconia-based ceramics. Regarding resin cements modified the surface treatment has become indispensable to enable improvement in bond strength. Treatment with silica coverage with or without the primer presented with better results. Regarding the self-adhesive cement, surface treatment had no major influence on the bond strength but better results were obtained on surfaces treated with the coverage of silica. After thermocycling was observed that the self-adhesive cement had values better adhesion strength in comparison to the modified resin cement.

The main goal of this diploma´s thesis is to review final qualities of traditional porcelain body with using nanofibers. The theoretical part of the thesis summarizes the current knowledge of the research on ceramic composite with using nanofibers. The vast majority of these researches is engaged by reinforcing technical ceramics, on the other hand area of traditional porcelain is still unexplored area. Besides that there are shown technological ways of the production and dispersion of the most important types of nanofibers. In the practical part of this thesis is experimentaly defined the most effecient way of homogenization procedure and the most effecient dose of nanofibers for pure kaolin body. In conclusion are compared the resulting properties of traditional porcelain body with using Al2O3 and SiO2 nanofibers.

This work deals with bioceramic materials based of hydroxyapatite, bioglass and their composites. These materials are commonly used in medicine, especially as hard tissue substituents. They can be prepared by different types of syntheses, from which the most common were picked for this work – precipitation of hydroxyapatite and sol-gel method for bioglass. Thermal analysis and X-ray diffraction were used for characterization of prepared powders. This thesis studies mostly their features within the composite materials, which were foamed for better bone stimulation. Properties and possibility in bio application of materials is firstly studied through their interaction in simulated body fluids, which mimics ionic concentration of human plasma. Experimental part covers synthesis of ceramic powders, their characterization, preparation of mixtures and scaffolds foamed through in situ foaming, their sintering at ideal temperatures, characterization of porosity and phase changes due to sintering. Basic tests of apatite formation ability were provided by incubation of prepared scaffolds in simulated body fluid for 3, 7, 14 and 21 days and their assay in scanning electron microscopy. Changes in concentration of Ca2+ a PO4 3- ions as well as in weight of the specimen were tracked within the incubation period.

No description available.

Silicon nitride thin films are of interest in the biomedical engineering field due to their biocompatibility and favorable tribological properties. Evaluation and understanding of the properties of these films under diverse loading and failure conditions is a necessary prerequisite to their use in biomedical devices. Three wafers of silicon nitride-coated silicon were obtained from Lawrence Livermore National Laboratory and used to create 96 samples. Samples were subjected to nanoindentation testing to evaluate the mechanical properties of the film. Samples were subjected to nanoimpact testing to compare the damage resistance of the film to separate nanoimpact types. Samples were subjected to nanoscratch testing to evaluate the consistency of the critical load of the film. Results showed that there were no significant differences in the mechanical properties of the film across the tested groups. There was a significant difference observed in the rate of damage to the film between pendulum oscillation nanoimpact testing and sample oscillation nanoimpact testing, with the former causing more damage with all experiment variables controlled for. Results showed that the critical load measure for the film was significantly different between different nanoscratch test parameters. The conclusions from this study will support future work for in vitro and in vivo testing of ceramic thin films for biomedical applications.

The theme of this thesis is the engineering design of the automaton for the ceramic moulds production for the shell casting technology. In the first part of the thesis I occupy with the design of the mechanical part of the machine including the kinematic, dynamic and strength calculations of the chosen engineering compositions and components. In the next part of the thesis I design the control part of the machine.

Des céramiques piézoélectriques sans-plomb de composition (CazBa1-z)(Ti1-x-wCoxNbw)O3- ont étésynthétisées e Li2O ou de Li2CO3des matériaux denses à une température de 1100 °C au lieu des 1300 °C usuellement requis pour fritter leBaTiO3.fonctionnelles : le coefficient piézoélectrique d33 et le coefficient de couplage kp atteignent respectivement255 pC/N et 43,5%. De plus, un recuit sous O2 des échantillons dopés au cobalt mène à un d33 = 265 pC/Net à un kp = 42,8%.En fonction de la nature des dopants, un caractère « doux » ou « dur » a été observé dans les céramiquespiézoélectriques. Le dopage par les ions Co/Li mène à un comportement « dur » et provoque desphénomènes de vieillissement. On observe ainsi pour un BT:Co,Li vieilli, un cycle P = f(E) àdouble boucle ou déformé pour des échantillons respectivement non-polarisés ou polarisés. Les cyclescours du temps. Ce champ inCes phénomènes particuliers sont dus à la formation de dipôle de défaut (MTi VO )x causée parin, les grandes valeurs ducoefficient de qualité mécanique (Qmsynthétisées vis-à-vis de fortes contraintes, mécanique ou électrique. Cela rend ces matériaux compétitifscomparés au PZT 4 pour des applications de type transduction acoustique. / (CazBa1-z)(Ti1-x-wCoxNbw)O3- lead-free piezoelectric ceramics were prepared using solid-state reaction. Theuse of a Li2O or Li2CO3 sintering aid enables one to obtain dense ceramics at a temperature of 1100 °Cinstead of the 1300°C used for BaTiO3 in conventional sintering. Insertion of Li/Ca/Co/Nb in the perovskitestructure improves functional properties: for micrograin-size ceramics, a piezoelectric charge constant andelectromechanical coupling factor of d33 = 255 pC/N and kp = 43,5% were reached, respectively.Furthermore, a thermal annealing of the cobalt doped sample under O2 atmosphere led to d33 = 265 pC/Nand kp = 42,8%.Soft/hard characteristics of the piezoelectric ceramics are observed depending on the dopant ions. The Co/Liacceptor dopants lead to hard piezoelectric ceramics and aging phenomena. The aged BT:Co,Li exhibitsdouble loops and a distorted hysteresis cycle for non-poled and poled ceramics, respectively. Distortedhysteresis loops for BT:Co,Li show an increased internal bias field with aging time. Insertion of donordopants such as niobium ions significantly reduces the internal field. These behaviors are related to thepresence of defect dipoles (MTi VO )x due to the insertion of acceptor dopants in the B sites following theoxygen vacancies to equilibrate charge compensation. The high mechanical quality factors (Qm > 1000)obtained for the doped BaTiO3 ceramics affords stability against mechanical stress and electrical stress of upto 400 VRMS/mm, which makes these materials competitive with PZT4 for acoustic transducer applications.

Ceramic membranes (CM) are robust membranes attributed with high production, long life span and stability against critical conditions. While capital costs are high, these are partially offset by lower operation and maintenance costs compared to polymeric membranes. Like any other low-pressure membrane (LPM), CM faces problems of fouling, low removal of organic matter and poor removal of trace organic compounds (TOrCs). Current pretreatment approaches that are mainly based on coagulation and adsorption can remove some organic matter but with a low removal of the biopolymers component which is responsible for fouling. Powdered activated carbon (PAC) accompanied with a LPM maintains good removal of TOrCs. However, enhanced removal of TOrCs to higher level is required. Submicron powdered activated carbon (SPAC), obtained after crushing commercial activated carbon into very fine particle, and novel activated carbon (KCU 6) which is characterized with larger pores and high surface area were employed. A pre-coating approach, which provides intimated contact between PAC and contaminants, was adopted for wastewater and (high DOC) surface water treatment. For seawater, in-line coagulation with iron III chloride was adopted. Both SPAC and KCU 6 showed good removal of biopolymers at a dose of 30 mg/L with > 85 % and 90 %, respectively. A dose of 40 mg/L of SPAC and 30 mg/L KCU 6 pre-coats were successful used in controlling membrane fouling. SPAC is suggested to remove biopolymers by physical means and adsorption while KCU 6 removed biopolymers through adsorption. Both KCU 6 and SPAC attained high removal of TOrCs whereas KCU 6 showed outstanding performance. Out of 29 TOrCs investigated, KCU 6 showed > 87 % TOrCs rejection for 28 compounds. In seawater pretreatment, transparent exopolymer particles (TEP) were found to be an important foulant. TEP promoted both reversible and irreversible fouling. TEP are highly electronegative while alumina CM is positively charged which support strong TEP–alumina binding. The influence of TEP fouling was minimized with a low dose of 0.5 – 1 mg/l Fe coagulant. Bacteria were almost completely removed; Silt Density Index (SDI) value was maintained to 2 % per minute and a constant permeate turbidity of 0.05 NTU was achieved.