bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuum Isotropic Elastic Model for Sintering of Ceramic Materials
Authors: Serrano Vergel C. , Escobar Jairo Arturo , Porras G.O.
Published: August 2012

In this work a sintering model that assumes infinitesimal displacements rates has been structured using the continuum theory of sintering develop by Olevsky and Skorokhod [1, 2] and the sintering model develop by Sasan Kiani et al. [3, 4]. The model was used to estimate dimensional change and the density distribution using linear displacement rates (LRDs) as the only input. Furthermore, if the sintering potential and dense material shear viscosity are known, the stress distribution can be approximated. The magnitude of two stress norms (i.e. Von Misses stress and the stress tensor first invariant) determined using experimental and calculated LDRs are compared using three different geometries. From FEM simulation results it was inferred that densification can occur in presence of tension stresses if their magnitude is lower than the calculated sintering potential.
Thermogravimetric Study of the Oxidation Behaviour of Sintered Stainless Steels: Influence of Powder Size and Composition
Authors: Moral Cristina , Bautista Asuncion
Published: August 2012

The oxidation resistance at high temperature of the sintered stainless steels highly depends on their porosity and composition. In this work, 9 different powder mixes of gas atomized (ga) and water atomized (wa) particles were prepared.waferritic AISI 434L was used as base material, mixed in different amounts (5-20% by wt.) withgaaustenitic AISI 316L orgaferritic AISI 430L. All materials were vacuum sintered at two temperatures (1175 and 1225 °C). Thermogravimetric curves of the materials at 800 °C were obtained. Logarithmic curves are used to fit the experimental mass gains of PM steels. The addition ofgapowder to thewapowder reduces the kinetic constant (k) in a remarkable way. The value ofkdepends on the amount of small pores that become blocked by the oxides when the exposure at high-temperature takes place. For similar porosity values, pure ferritic alloys show slower oxidation kinetic than duplex stainless steels.
Microstructural and Mechanical Properties Changes of Silicon Nitride Based Ceramic Using Post-Sintering Heat Treatment
Authors: Souza José Vitor C. , Silva O.M.M. , Raymundo E.A. , Machado João Paulo Barros
Published: August 2012

Si3N4based ceramics are widely researched because of their low density, high hardness, toughness and wear resistance. Post-sintering heat treatments can enhance their properties. Thus, the objective of the present paper was the development of a Si3N4based ceramic, suitable for structural applications, by sintering in nitrogen gas pressure, using AlN, Al2O3, and Y2O3as additives and post-sintering heat treatment. The green bodies were fabricated by uniaxial pressing at 80 MPa with subsequent isostatic pressing at 300 MPa. The samples were sintered at 1900°C for 1 h under N2gas pressure of 0.1 MPa. Post-sintering heat treatment was performed at 1500°C for 48 h under N2gas pressure of 1.0 MPa. From the results, it was observed that after post-sintering heat treatment there was a reduction of α-SiAlON phase and increase of β-Si3N4phase, with consequent changing in grain size, decrease of fracture toughness and increase of the Vickers hardness.
A Critical Analysis of the Importance of Compaction-Pressure on the Dimensional Distortion of ZrO2-Y2O3 Dental Prostheses
Authors: Silva A.A.A.P. , Rodrigues A.S. , Freitas R.X. , Cury S.E.N. , Suhett I.V.F. , Santos C.
Published: August 2012

In this work, the effect of pressure and direction of compression in the shrinkage and flatness of ZrO2-(Y2O3) dental ceramics were studied. Samples (40x15x15mm) were uniaxial cold pressed at different pressures ranging from 10MPa to 160MPa, and then pre-sintered for further cutting. For comparison, samples were also isostatically cold pressed at 300MPa. The pre-sintered samples were cut longitudinally and transversely to the direction of compression, with final thickness of 1mm. Then the samples were ground and polished, and measured with a micrometer at different positions of the sample. After the measurements, the samples were sintered at 1530C-120 min, and again measures. The results indicate the effect of pressure decline in considerable amounts, up to pressures of about 80MPa. Above this value the differences in shrinkage and warpage are insignificant when compared to isostatically pressed samples.
Evaluation of Mechanical Properties of Dental Feldsphatic Porcelains for Metal and Zirconia Core
Authors: de Almeida-Junior Antonio Alves , Adabo Gelson Luis , Galvão Beatriz Regalado , Longhini Diogo , dos Santos Claudinei
Published: August 2012

Studies has been reported a significant incidence of chipping of the feldspathic porcelain veneer in zirconia-based restorations. The purpose of this study was to compare the three-point flexural strength (MPa), Weibull parameters, Vickers hardness (VHN) and Vickers indentation fracture toughness (MPa/mm1/2) in feldspatic porcelains for metal and for zirconia frameworks. Bar specimens were made with the porcelains e.MaxCeram (EM) and VitaVM9 (V9) for zirconia core, and Duceragold (DG) and VitaVMK95 (VK) for metal core (n= 15). Kruskal-Wallis and Dun test were used for statistical analysis. There was no significant difference (p=0.31) among the porcelains in the flexural strength (Median= 73.2; 74.6; 74.5; 74.4). Weibull calculation presented highest reliability for VK (10.8) followed by EM (7.1), V9 (5.7) and DG (5.6). Vickers hardness test showed that EM (536.3), V9 (579.9) and VK (522.1) had no difference and DG (489.6) had the lowest value (p.001). The highest fracture toughness was to VK (1.77), DG (1.58) had an intermediate value while V9 (1.33) and EM (1.18) had the lowest values (p.001). Despite of the suitable flexural strength, reliability and high hardness, the porcelains used to zirconia-based fixed dental prostheses showed lower fracture toughness values.
Characterization Optical of ZnAl2O4 Doped with Eu3+ Functionalized with Chitosan
Authors: Santos P.T.A. , Furtado Cristiane M. , Rodrigues M.O. , Costa A.C.F.M.
Published: August 2012

ZnAl1.,9Eu0.1O4nanoparticles were functionalization used of the 3-aminopropyltrimethoxysilane silane and chitosan, in 5:1 proportion of the nanoparticles to chitosan, in order to obtain hybrid materials for the development of luminescent markers. The samples were characterized by XRD, FTIR, TEM, excitation and emission. After functionalized the nanoparticles showed formation of crystalline phase of spinel and chitosan. TEM results have revealed that the samples presented before particle size less than 100 nm and after functionalization was observed that the particle size increases. Emission peak of Eu centered at 614 nm, corresponding to the transition5D07F2. Nanoparticles before and after functionalization showed the spectral lines characteristics of Eu ion5D07Fjwhere (J = 0,1,2,3,4). After functionalization the sample presented an increase of luminescence intensity.
Antibacterial and Antifungal Glass with High Biocide Performance: Increased Antimicrobial Efficiency by Acid Activation
Authors: Mendes Elton , Oliveira C.M. , Tachinski C.G. , Fernandes M.P. , Piletti Raquel , Riella Humberto Gracher , Fiori Márcio A.
Published: August 2012

A compound contending silver ion specimens presents biocidal properties with effect proportional to ion concentration. An efficient biocidal material can be developed by incorporating silver ions species in glasses by ionic exchange process. The reactive area and material porosity are factors that influence the ion exchange reaction efficiency. Previous studies show that the acid activation of glasses increases the absorption capacity and can also increase the exchange capacity. This paper presents preliminary results on the biocide potencial optimization of the biocide powder glass. This process was performed using hydrochloric acid. Different pH (1.00, 3.00 and 5.00), treatment time (2.0, 4.0 and 6.0 hours) and temperature (30.0, 60.0 and 90.0°C) were used in the samples development. Microbiological analysis of the samples was made by disk diffusion method in the bacteria species Echerichia coli and Staphylococcus aureus. Samples were still submitted to EDS and Atomic Absorption.
Utilization of Solar Energy as Heat Source
Authors: Prado G.O. , Arouca A.M.M. , Domingues R.C.C. , Vieira Luiz Gustavo Martins , Damasceno João Jorge Ribeiro
Published: August 2012

The search for energetic alternatives and the concern about water preservation are novel ideas that challenge the humanity. This project was inspired in these challenges, being based in the utilization of solar energy for desalination of brackish water. A parabolic solar concentrator captures the solar radiation heating thermal fluid, which is closed-circuit circulated into a evaporator, which has three trays. The first has the functions of storing, pre-heating and condensing. The second works as an evaporator and the third stores the evaporated water. The system was tested with and without pump. The thermal fluid temperature reached 105°C and the amount of evaporated water reached 15kg/day. The equipment meets the social demand for sustainable inventions.
Lithium Disilicate Bioceramic Obtained from Alternative Silica Source, the Rice Husk
Authors: Santos Felipe Antunes , dos Santos Claudinei , Rodrigues Júnior Durval , Pinatti Daltro Garcia , Davim Erika , Fernandes Maria Helena F. V.
Published: August 2012

The crystallization process of lithium disilicate glass-ceramic with SiO2 from rice husk silica replacing the high-purity SiO2 starting powder has been investigated in this work. Glasses were developed at the stoichiometric composition of 66%.molSiO2:33%.molLiO2 using commercial SiO2 and the one obtained by thermochemical treatment of rice husk. The influence of rice husk-SiO2 on crystallization process to different granulometry, microstructure and kinetic behavior was determined and discussed. Investigations were carried out by means of differential thermal analysis (DTA), X-ray fluorescence (XRF), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Amorphous and transparent glasses were obtained after melting. The lithium disilicate glass-ceramic crystallization peaks (Tp) are between 550 to 660°C to different granulometry (<63μm, 63μm < x < 250μm and 1mm < x < 2mm) and DTA heat rates (5; 10; 15; and 20°C/min) in both glasses from different silica sources, and the formed phase was Li2Si2O5 as the crystalline phase after DTA thermal analysis as XRD confirmation. Improve in mechanical properties were estimated by morphological analysis of the microstructure modification in increasing the heat treatments temperature by SEM. The increase of glass substitution for crystalline phase was also observed with SEM images to both glass-ceramics from different silica sources.
Polydimethylsiloxane/Calcium Phosphates Composites: Effect of the Fillers Modification on the Cross-Linking and Surface Energy
Authors: Bareiro Oscar F. , Santos Luis Alberto
Published: August 2012

A potential approach to achieving the objective of favorably modulating the biological response of implantable biopolymers combined with good mechanical properties is to consider compounding the biopolymer with a bioactive nanocrystalline ceramic biomimetic material with high surface area. In this work, n-HAp (nanohydroxyapatite) and n-α-TCP (nanoα-tricalcium phosphate) powders were modified by silane coupling agent and mixed with poly (dimethyl siloxane) gum so nanocomposites could be achieved. The influence of the introduction of modified and unmodified calcium phosphate particles on the composite thermodynamics parameters of cross-linking, static contact angle and surface energy were investigated. It was found that the dispersion state of modified particles in the silicone matrix was homogeneous. The introduction of fillers into the silicone matrix changed the enthalpy of cross-linking. The addition of unmodified particles led to higher surface energy values, on the other hand, modified particles led to lower surface energy values.
A Simple Algorithm for the Calculation of Hysteresis for Isotropic NdFeB Magnets
Authors: Sampaio da Silva Fernanda A. , de Campos Marcos Flavio
Published: August 2012

The calculation of hysteresis curves with the Stoner-Wohlfarth model is somewhat laborious. For the Nd2Fe14B phase, the second order magnetocrystalline anisotropy (K2) constant is relevant, and this case only has been discussed in some studies. In this article, a simple algorithm for the calculation of the Stoner-Wohlfarth model for isotropic NdFeB magnets is described. This algorithm makes easier the modeling of the hysteresis curves of bonded melt-spun NdFeB magnets.
Obtaining of Nanoapatite in Ti-7.5Mo Surface after Nanotube Growth
Authors: Escada A.L.A. , Machado João Paulo Barros , Nakazato Roberto Zenhei , Rosifini Alves Claro Ana Paula
Published: August 2012

Titanium and their alloys have been used for biomedical applications due their excellent mechanical properties, corrosion resistance and biocompatibility. However, they are considered bioinerts materials because when they are inserted into the human body they are cannot form a chemical bond with bone. In several studies, the authors have attempted to modify their characteristic with treatments that changes the material surface. The purpose of this work was to evaluate obtaining of nanoapatite after growing of the nanotubes in surface of Ti-7.5Mo alloy. Alloy was obtained from c.p. titanium and molibdenium by using an arc-melting furnace. Ingots were submitted to heat treatment and they were cold worked by swaging. Nanotubes were processed using anodic oxidation of alloy in electrolyte solution. Surfaces were investigated using scanning electron microscope (SEM), FEG-SEM and thin-film x-ray diffraction. The results indicate that nanoapatite coating could form on surface of Ti-7.5Mo experimental alloy after nanotubes growth.
Ferrite Ni0,5Zn0,5Fe2O4 Synthesized by Combustion Reaction in a Microwave Oven Using Urea and Glycine as Fuel: Influence of Power
Authors: Vieira Débora A. , Diniz Verônica Cristhina S. , Kiminami Ruth Herta Goldsmith Aliaga , Cornejo Daniel R. , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

This paper reports the preparation of ferrite Ni0,5Zn0,5Fe2O4by combustion reaction in a microwave oven, and its structural, morphological and magnetic characterization. The influence of microwave power and the fuel type was investigated. The samples were characterized by: XRD, BET, SEM and AGM. The results showed the formation of phase ferrite Ni0, 5Zn0,5Fe2O4in all conditions evaluated. The presence of secondary phase hematite and nickel were observed only in samples with glycine. The microwave oven power and the fuel type altered the structure, morphology and magnetic behavior of the samples. In general, the samples synthesized with urea are promising for applications in catalysis, ferrofluids, magnetic sensors and the samples synthesized with glycine are promising for use as absorber electromagnetic radiation, due to the large particle size and good magnetic characteristics observed.
New Routes Study for Synthesis of Molecular Sieves Type Al-MCM-41 and Al-SBA-15
Authors: de Miranda Rafaela Pereira Roque , Santos José Otávio Peroba Nascimento , Alves José Jailson Nicácio , Brito Romildo Pereira , de Sousa Bianca Viana
Published: August 2012

The areas of research, synthesis and catalytic application of zeolites as molecular sieves are a field of great development and prominence in recent decades. Needs of the industries of petrochemical and fine chemicals have been encouraging specific studies for the application of molecular sieves looking for technological, commercial, and more recently sustainable developments. In this work molecular sieves type Al-MCM-41 and Al-SBA-15 has been synthesized using new synthesis routes by replacing the silica source conventionally used by rice husk. The molecular sieves obtained were confirmed by X-ray diffraction. Through the thermograms the decomposition of the driver at different temperatures was noticed. According to SEM micrographs can be observed that the material shows an aggregate of relatively uniform short particles.
Evaluation of the Apatite Coating on Silicon Nitride Based Ceramics Sintered with Re2O3 Additives (Re = Y, La, Yb)
Authors: Marchi Juliana , Guedes e Silva Cecília Chaves , Rigo E.C.S. , Bressiani Ana Helena de Almeida , Bressiani José Carlos
Published: August 2012

As alternative for alumina and zirconia implants, silicon nitride based ceramics are considered promising candidate due to its biocompatibility and mechanical properties. However, this materials exhibit a bioinert character, leading to clinical failures. To overcome this problem, a biomimetic coating of hydroxyapatite is proposed in this paper, so that the surface can be bioactive and, consequently, the osteointegration process can be enhanced. Silicon nitride samples were sintered with different additives (Y, La and Yb) and the surfaces before and after coating were characterized by diffuse reflectance infrared Fourier transformed (DRIFT), X ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the surfaces of bioinert silicon nitride samples sintered with different additives could be transformed into bioactive by the formation of a hydroxyapatite layer through biomimetic process.
Influence of the Urea Content in the Combustion Synthesis for Preparation of NiAl2O4 Support Catalytic to Steam Reforming of Methane
Authors: Leal Elvia , Andrade Heloysa Martins Carvalho , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

The aim of this work is to evaluate the catalytic performance in steam reforming of methane of the NiAl2O4catalysts prepared by combustion reaction with different urea levels. The catalysts were prepared with urea in the stoichiometric proportion, and with excess of 10% and 20%. The samples were characterized by DRX, textural analysis by nitrogen adsorption, SEM, TPR, and then, catalytically evaluated in the methane reforming reaction. The results showed the presence of NiAl2O4and traces of NiO for all the samples. The increase of the urea content caused an increase in the particle size and a reduction in the surface area, from 171 to 35 m2/g. All the samples presented irregular morphology. The TPR curves showed peaks of reduction of the NiO species, and reduction of nickel present in the NiAl2O4. Regarding the conversion of methane to synthesis gas, it was observed that the increase of the urea content allowed obtaining higher conversion. However, it was also observed a rapid deactivation of these catalysts due to high coke deposition on the active phases surfaces.
Influence of the Ratio between the Amounts of Reagent Total/H2O to Obtain Ferrites Mn0.65Zn0.35Fe2O4 by Combustion Reaction
Authors: Santos R.L.P. , Leal Elvia , Silva A.T.C. , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

This work proposes to study the influence of dilution on the synthesis of ferrites Mn0.65Zn0.35Fe2O4 using glycine. It was used the reactants/H2O proportions of 1:0; 1:3.5; 1:7; 1:10, and 1:14 (100 mL of H2O). During the synthesis were measured the time and temperature of combustion. The samples were characterized by X-ray diffraction and X-ray fluorescence. The dilution in the samples increased with the increasing of the reaction time and flame temperature. For samples synthesized with 1:0, 1:3.5; and 1:7 ratio were observed traces of hematite, and to the remaining samples only the single phase of the Mn0.65Zn0.35Fe2O4 spinel. The crystallite sizes ranged from 32 to 42 nm.
Synthesis and Characterization of Gadolinia-Doped Ceria with Manganese Addition
Authors: Yang J.D. , Rocha R.A. , Muccillo R. , Muccillo E.N.S.
Published: August 2012

Ceria-based materials have been extensively studied due to their wide range of technological application. In this work, nanostructured powders of 20 mol% gadolinia-doped ceria pure and containing 1 mol% manganese were synthesized by the cation complexation technique. Powder materials were calcined at 600°C, uniaxially pressed and sintered in the 1200-1500°C range for soaking times of 1, 2 and 4 h. X-ray diffraction patterns evidenced a single-phase fluorite-like structure in all studied specimens. The evolution of grain sizes was evaluated by scanning electron microscopy on polished and thermally etched surface of sintered pellets. The relative density decreases for soaking times above 1300°C (with Mn) and 1400°C (without Mn). The grain size increases with manganese addition. The role of the additive on the electrical conductivity of gadolinia-doped ceria was evaluated by impedance spectroscopy measurements.
Synthesis of Inorganic Pigments from Glass-Ceramics of System Li2O-ZrO2-SiO2 and Waste from Metallurgical Industry
Authors: Schmitt T.J. , Tomiyama M. , Folgueras Marilena Valadares , Bahr F.L.
Published: August 2012

In the ceramic coating industry, color and its stability influence the visual appearance of the product. These features account for the growing interest in obtaining pigments that are stable and may optimize the process. There are different synthesis routes to obtain pigments. Obtaining glass and its subsequent crystallization is an alternative proposed in the literature. This study focuses on the possible use the glass of the Li2O-ZrO2-SiO2 system as base glass and hematite as chromophore source. Different contents of hematite (1%, 2%, 3%), from the beneficiation process of metal sheets were used. The choice of composition aimed at facilitating the devitrification process for the formation of zirconia, which is often used as an encapsulating matrix in inorganic pigments. Results showed that glass synthesis is feasible and the effect of crystallization in the presence of hematite is favored, so an effective pigmenting effect is expected.
Precursors Influence on CaCu3Ti4O12 Synthesis
Authors: Gelfuso Maria Virginia , Lima Gabriel Moreira , Thomazini Daniel
Published: August 2012

In this work CCTO have been synthesized in two different chemical precursors: calcium hydroxide and copper sulfate were used to compose CCTO-S powder while calcium carbonate and copper nitrate were used to form CCTO-N powder. Calcinations conditions were dramatically different in terms of shelf time and temperature. The CCTO phase was fully obtained for 3 hours of calcination in CCTO-N against the 24 hours to form the same phase in CCTO-S powder. Ceramic bodies densities values for CCTO-S samples were 95% of theoretical density (5.05 g/cm3) and 98% for CCTO-N. The dielectric constant, at room temperature, was obtained for ceramics processed by two routes. Microstructural analysis was conducted by Scanning Electron Microscopy (SEM) and it was performed to explain the dielectric constant differences between CCTO-S and CCTO-N ceramics.
New Features Regarding the High Pressure and High Temperature Diamond Synthesis Growth in the Ni-Mn-C System with Iron Additions
Authors: Skury Ana Lucia D. , Rodrigues Quesia F.S.F. , Bobrovinitchii Guerold Sergueevitch , Monteiro Sérgio Neves
Published: August 2012

t is well recognized that a catalyst agent is essential to synthesize diamond at high pressure and high temperature. The catalyst agent also acts as a carbon solvent and affects the properties of the final product. This is a consequence of its direct influence on the growth of diamonds crystals. The control of the growth, which is required to achieve a high quality level, is still a question open to discussion. In this work, an industrial diamond powder was synthesized from graphite using Ni-Mn as catalyst alloy added with up to 5% of iron. The synthesis was carried out at 4.5GPa and 1300°C for 10 minutes in high pressure device with central concavity. The analysis of the cubic-shaped diamond surface topography suggests that the formation of defects on the {111} faces is most likely a consequence of a complex growth process that influences the crystal productivity and morphology.
EBSD Texture Analysis of NdFeB Magnets
Authors: Hauegen Christien G. , da Silva Fabiane R. Freitas , Sampaio da Silva Fernanda A. , Lins Jefferson Fabricio Cardoso , de Campos Marcos Flavio
Published: August 2012

The crystallographical texture is relevant information for NdFeB magnets, since the maximum energy product is directly related to orientation of the crystals. EBSD (Electron Backscattered Diffraction) is a very suitable tool for preferred orientation measurement of NdFeB magnets. The advantages of EBSD against X-ray Diffraction (XRD) pole figures for texture determination are discussed. EBSD identifies misaligned grains, and this is not feasible with XRD pole figures. EBSD is also helpful on the identification of oxides.
Paramagnetic Properties of Synthetic Diamond Crystals Obtained in Ni-Mn-C System with Iron Doping
Authors: Skury Ana Lúcia Diegues , Bobrovinichii Guerold S. , Monteiro Sergio N. , Rodrigues Quesia F.S. Fonseca
Published: August 2012

Diamond crystals were synthesized at 4.5GPa and 1300°C in a Ni-Mn-C system with and without Fe doping. The reactive mixture was prepared with 50 wt% graphite and 50 wt% Ni-Mn followed by doping of 2 to 5wt% of pure iron. The synthesis was performed inside an anvil type high pressure device. After extraction and purification, the paramagnetic properties of the diamond crystals were evaluated by specific techniques at room temperature. It was found that the diamond synthesized with different iron content exhibit different paramagnetic properties. The data obtained by infrared spectroscopy and electron spin resonance (ESR) spectroscopy are coincident for radiation defects and different for nitrogen centers. The spectra of the electron spin resonance exhibited broad lines produced by residual impurities of Fe compounds together with catalyst alloy and were accompanied by a distortion of the spectrum of paramagnetic nitrogen in the form of a tilt of the ESR spectra with respect to the zero line.
Synthesis and Characterization of Porous ZrO2-Y2O3-TiO2 Ceramics Prepared by Coprecipitation
Authors: Medeiros Luan M. , Silva Fernando S. , Marchi Juliana , Yoshito Walter Kenji , Lazar Dolores Ribeiro Ricci , Ussui Valter
Published: August 2012

Zirconium dioxide (zirconia) ceramics are known by its high strength and toughness and titanium dioxide (titania) ceramics has outstanding surface properties. The ceramic composite formed between the two oxides are expected to have advantages of both ceramics, especially when its surface area is increased by pores. In this work, ceramic composites of ZrO2-Y2O3-TiO2were synthesized by coprecipitation and rice starch was added as pore former in 10, 20 and 30 wt%. Powders were cold pressed as cylindrical pellets and sintered at 1500 °C for 01 hour and ceramics were characterized by techniques as Archimedes method for density measurements, X-ray diffraction and scanning electron microscopy. Results showed that pores are inhomogeneously distributed through ceramic bodies.
Ceramic Material from Sewage Sludge as Support Material Supply Water Filtration
Authors: Morais Leandro C. , Rosa A.H. , Fraceto L.F. , Toledo A.C.T. , Campos V.
Published: August 2012

This study shows a possibility of using municipal sewage sludge after thermal treatment in the production of a filtering material to water treatment. Due to the fast urbanization and implementation of high standards for effluent in many countries in recent years, the sewage sludge is being produced in an ever increasing amount. Therefore, the use of sludge is a suitable solution for the expected large quantity of sludge. Dehydration of sludge was performed by controlled heating at temperatures of 1100°C, 850°C, 650°C, 350°C for 3 hours. After thermal treatment the sludge was characterized by X-ray fluorescence, TG/DTG/DTA, residue solubilization and residue lixiviation tests. The aim of the present work was to observe, thought the characterization techniques, if the treated sewage sludge is or not adequate to be used as filter material to water treatment. It will be verified which treatment temperature of the sludge offer possibility to its use in water treatment without carrying pollutants in concentrations out of the standards.
Soil-Lime Blocks Using Construction Residues - Durability Study
Authors: Figueiredo Suélen Silva , Silva Cibelle Guimarães , Bezerra Izabelle Marie Trindade , Dias Suellen Lisboa , Neves Gelmires Araújo , Menezes Romualdo Rodrigues , de Lima Santana Lisiane Navarro
Published: August 2012

The construction industry in addition to being considered one of the biggest natural resources consumers is still responsible for generating large quantities of residues. The impacts caused by these residues have motivated research aimed at developing new techniques for reuse and recycling this material by using as raw material to make alternative materials. The introduction of demolition residues (DR) in soil-lime bricks replacing part of the pozzolan becomes possible due to the cementing properties that these residues may present when finely grounded. This study aims to evaluate the durability of soil-lime blocks embedded with demolition residues. For this study the raw materials were characterized by particle size distribution analysis, X-ray diffraction and chemical analysis. Then test specimens were prepared using mixes in a 1:10 ratio of lime:soil and embedded with residue in partial replacement of lime, in the proportions of 25%, 50% and 75% with curing period of 90 days. Later, the test specimens were evaluated for durability. The results showed that soil-lime bricks embedded with contents above 50% of residues had their durability affected.
Purification of Bentonite Clays from the District of Cubati, PB, for Obtainment of Organoclays for Use in Drilling Fluids
Authors: de Figueirêdo J.M.R. , da Silva Carla Dantas , da Silva Isabelle Albuquerque , Ferreira Heber Sivini , Neves Gelmires Araújo , Ferreira Heber Carlos
Published: August 2012

The main deposits of bentonite clays are located in the district of Boa Vista, in the State of Paraiba, Brazil. The random exploration of these deposits for many years is causing the clays to be depleted, and this will turn into a serious problem to the national petroleum industry. So, this work aims to study the characterization of new deposits of bentonite clays in the district of Cubati, in the State of Paraiba, Brazil, with the objective of developing purified organoclays, using a hydrocyclone, from ionic and non-ionic surfactants for use in drilling fluids. The characterization of the studied clay samples was done by applying the following techniques: granulometric analysis by laser diffraction (GA), X-ray diffraction (XRD) and chemical analysis by X-ray fluorescence (EDX) and thermogravimetric (TGA) and differential thermogravimetric (DTA) analysis. The characterization is typical of bentonites and the dispersions present rheological properties which meet Petrobras’ specifications for diesel oil media, organofilized with Praepagen WB.
Bi4Ti3O12 Particles Size Influence on Electrorheolocical Response
Authors: da Silva Luz Glauber Márcio , Gelfuso Maria Virginia , Thomazini Daniel , Pinto Pedro Perri , Bombard Antônio José Faria
Published: August 2012

Electrorheological uids (ER) are commonly known as suspensions composed of semiconducting particles dispersed in insulating oil that respond to electric fields by gelling. The increase in suspension viscosity on application of the field is typically rapid and reversible and as a result, the ER response is amenable to applications where real time control of stress transfer properties is required. Ferroelectric particles are interesting in this application due to the presence of spontaneous polarization and high dielectric constant. Particularly, Bismuth Titanate (Bi4Ti3O12 - BIT) is well-known as layer-structured ferroelectrics, so the typical morphology of these crystals is lamellar. Therefore, these particles dispersed in oil, in the presence of an electric field must produce an interesting ER response. Thus, BIT powders were prepared by the conventional solid state reaction method and the particles size was adjusted using ball milling process. Different ER fluids containing average particles size about 2.5 to 0.5 μm were dispersed in silicon oil about 10% vol and were submitted to AC and DC electric field. The relation between the BIT particles size with the ER response was observed, presenting an increase of the shear stress with the reduction on particle size.
Nucleus Size Determination for Nd2Fe14B, Sm2Co17, SmCo5 and BaFe12O19 Magnets
Authors: de Campos Marcos Flavio , de Castro José Adilson
Published: August 2012

The nucleus size was determined for the following phases: Nd2Fe14B, Sm2Co17, SmCo5and BaFe12O19. These phases are the basis for the most relevant sintered permanent magnets. For the determination, it was assumed a spherical grain, and that the reversal of magnetization occurs in a tiny shell near the surface. The Magnetostatic energy for each domain configuration was found by means of Legendre polynomials. The nucleus is a spherical cap, near the equator. After reaching the nucleus critical size, the reversal of magnetization continues spontaneously, reducing the global energy of the system. It was found that, for each grain size, there is a different nucleus size.
Estudy of Natural and Degradation by Salt Spray of Red Ceramics Incorporated with Ornamental Rock Waste
Authors: Altoé Larissa Machado , Xavier Gustavo de Castro , Albuquerque Fernando Saboya , de Almeida Maia Paulo César , Alexandre Jonas , Pedroti Leonardo Gonçalves
Published: August 2012

To better study the mechanical behavior of red ceramic, the samples were degraded in salt spray equipment and exposed in environment. The salt spray equipment subjects the samples to conditions found by the sea, through the mix solutions of sodium chloride. The ceramic samples were prepared with up to 10% by mass of ornamental rock waste to dry and pressed into rectangular mold of steel. The materials were fired at temperatures of 650°C, 750°C and 850°C. After 90 days of degradation natural and 45 days in salt spray, ware analyzed the properties of ceramic material. The results of mechanical strength were compared using the Weibull distribution, before and after the degradation. Note that the material with ornamental rock waste raised the mechanical strength and didnt significantly changes the material properties after degradation.
Electronic Waste: Characterization of the Glass of Cathode Ray Tube Computer for Making Decorative Pieces by Recycling
Authors: Lima N.M.O. , da Silva Morais Crislene Rodrigues , Lima L.M.R. , Albuquerque A.V.
Published: August 2012

The vigorous industrialization of the modern world and the incorporation of new consumption habits of society made appears electronic waste. This work had as objective to collect and characterize vitreous residues originating from Cathode Ray Tubes or, popularly, "image tubes", identified for the acronym CRT, which integrate computers monitors that will be recycled in the production of handicrafts. For its characterization were used techniques: X-Ray Fluorescence, Granulometric Analysis, X-Ray Diffraction. After analyses it was observed that glasses of the screen and of the funnel presented different chemical compositions, being silicium oxide (SiO2) the component of larger percentage in these glasses, 59.89% and 48.63%, for screen and funnel, respectively. Funnel presented 29.47% of lead oxide (PbO) while this oxide is absent in the screen. Screen presents significant amounts of barium oxide (10.75%) and strontium oxide (7.71%). Vitreous samples X-ray diffractions of residues of the funnel and the screen are to each other similar, presenting an amorphous band that indicates silica presence, with absence of crystalline phases. Through the presented results can be concluded that computer monitors CRTs has potential for be recycled, because present great amounts of SiO2, oxide that forms the vitreous net.
Study of Adsorption Kinetics of Heavy Metals in Acid Drainage from Coal Mining in Type A Zeolites
Authors: Antunes Luciano , Angioletto Elídio , Melo Carolina Resmini , da Rocha Márcio Roberto , Madeira Alexandre Canarin , Mendes Erlon
Published: August 2012

The present work studied the adsorption of ions of iron and manganese of the effluent from coal acid mine drainage (AMD), located in South of the Santa Catarina using for this purpose type 4A zeolite. Were tested the Langmuir adsorption isothermal model. Tests of adsorption of heavy metals were performed by varying the adsorption time and the ratio of the volume of effluent and the amount of adsorbent. The results showed the efficiency of kinetic adsorption of iron and manganese ions by the zeolite.
Development of Organoclays for Use in Oil-Based Drilling Fluids
Authors: Cardoso Mirtys Allamana Ferreira , Ferreira Heber Sivini , da Silva Isabelle Albuquerque , Ferreira Heber Carlos , Neves Gelmires Araújo
Published: August 2012

The organoclays are derived from bentonite clays treated in aqueous solution with surfactants, which are incorporated into the interlayer surface of clays, covering them with an organic layer; so, the naturally hydrophilic clay becomes hydrophobic. This paper proposes a study to find the dispersant media (diesel, paraffin or ester) which is more suitable for use in fluids, using the bentonite clay Cloisite Na +, treated with ionic surfactants Praepagen HY and Praepagen WB. The organoclay obtained was characterized by X-ray diffraction, and we measured the apparent viscosity and plastic dispersions. We observed the importance of the type of surfactant and dispersant amid to obtain organoclays for non-aqueous drilling fluids with the dispersants that meet existing specifications for drilling oil wells.
Nonionic Surfactant Organoclays Obtaining from Pedra Lavrada District Clays, PB, Brazil
Authors: da Silva Isabelle Albuquerque , Costa Julliana Marques Rocha , Cardoso Mirtys Allamana Ferreira , Ferreira Heber Sivini , Neves Gelmires Araújo , Ferreira Heber Carlos
Published: August 2012

The State of Paraíba has large reserves of bentonite clays, mainly in the District of Boa Vista. New occurrences were recently discovered in the Districts of Pedra Lavrada and Cubatí, Paraíba, Brazil, creating great expectations for further expansion of reserves for industrial production. The use of nonionic surfactants is replacing the traditional ionic surfactants, among others, by its high resistance potential to thermal degradation. The objective is the development organoclays from Pedra Lavrada District PB, Brazil, clays, by adding non-ionic surfactants. The bentonites were organofilized and then characterized by X-ray diffraction (XRD), thermal analysis (TGA and DTA) and Foster swelling, seeking the most appropriate choice of surfactants to the diesel organic dispersing medium. The results showed that incorporation of surfactants used in the clay interlayer spacing increased significantly.
Investigation and Structural Characterization of Nickel Ferrite Nanoparticles Produced by Proteic Sol-Gel Method Using Two Kinds of Organic Precursors
Authors: Proveti José Rafael C. , Porto Paulo Sergio da Silva , Muniz E.P. , Pereira R.D. , Gobbi L.C.A.
Published: August 2012

Metallic oxide materials with AB2O4 structure are very interesting for technological applications. Nickel ferrite (NiFe2O4), for example, attracts considerable attention due to its chemical stability and mechanical hardness. These characteristics make it a suitable material for magnetic and magneto-optical applications. The properties of NiFe2O4 have a strong dependence on the crystallite size and microstructure. Due to this dependence, it is necessary to develop effective methods that allow controlling these variables. The aim of this work is to investigate the effect of time, temperature of isothermal treatment and choice of organic precursor during the production of NiFe2O4 samples employing the proteic sol-gel method have on crystallite size and microstructure. Two kinds of organic precursors were used: coconut water and pectin extracted from aple peel. Temperatures of 873 and 1173 K; 2, 4, 6, 8, 24 and 30 hours of isothermal treatment were also used. The samples produced were analyzed employing X-ray Diffraction.
Characterization of Fluorescent Lamp Glass Waste Powders
Authors: Morais Alline Sardinha Cordeiro , da Costa Caldas Thaís Cristina , Monteiro Sérgio Neves , Vieira Carlos Maurício Fontes
Published: August 2012

Industrialized component wastes, regularly discarded by the society, are increasingly contributing to the environmental pollution. The glass of these lamps is contaminated with mercury, which a serious hazard due to conventional recycling by melting with other glasses. A possible solution could be its incorporation into a clay body to fabricate common fired ceramics such as bricks and tiles. The objective of this work is to characterize a type of glass to be incorporated into a clayey ceramic. The glass analyzed was obtained from fluorescent lamps, which was passed through mercury decontamination process and ground into powder. This glass powder was tested for X-ray fluorescence, DTA/DTG, optical microscopy, scanning electron microscopy and optical dilatometry. The results showed that the glass presents sintering and softening points around 650 °C and 800 °C, respectively. The chemical analysis indicated the presence of impurities in considerable amounts in the composition of the fluorescent lamp glass waste.
The Behavior of Galvanized Steel Coated with a Double and Triple Layer of Hybrid Films
Authors: Kunst Sandra Raquel , dos Santos Rogério Freitas , Oliveira Cláudia Trindade , da Silva Elen Leal , Müller Iduvirges Lourdes , Malfatti Célia de Fraga
Published: August 2012

The aim of this work is to characterize by electrochemical, physicochemical and morphological analysis the hybrid films applied on galvanized steel by dip-coating process. Preliminaries studies showed that a monolayer of silane is not enough to increase the corrosion resistance protection of the substrate. In this context, the galvanized steel was coated with a double and triple layer of hybrid film obtained from a sol constituted by silane precursors 3 - (trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS) with addition of cerium nitrate at a concentration of 0.01M. The hybrid films were cured for 20 minutes at 60°C in each application of the film. The results showed that a double and triple layer of hybrid film increase the barrier effect contributing to corrosion protection of galvanized steel.
Study of Iron Nanopowders into Fluids of Industrial Lubrication
Authors: Oliveira Mabelle Biancarde , Souza Maryana Antonia Braga Batalha , de Castro José Adilson , da Silva Alexandre José
Published: August 2012

The machines and equipment has required increasing performance of lubricating fluids and coolants which plays important role on reducing friction with the metal parts and heat extraction. Viscosity and thermal conductivity are the most important properties of lubricants, in relation to the friction between the fluid molecules. This paper presents two useful models to predict this properties and their relation with the particles volume fraction and temperature in the nanofluid formed by adition of iron or particles produced by friction. Nanofluids are innovative heat transfer fluids with superior potential for enhancing the heat transfer performance of conventional fluids. In this paper the Unit Cell Model (UCM) which considers the Brownian movement experienced by the nanoparticles are adapt to predict the increment of thermal conductivity of iron nanopowders and standard lubrication oil. The viscosity of the nanofluids was adapt from a model usually suitable for predict the effective viscosity of emulsions. Model results indicated a strong effect of the particle size and volume fractions on the increment of thermal conductivity.
A Theoretical Study on BTX Adsorption into the Surface of Compacted Activated Carbon Powders
Authors: de Oliveira da Mota Izabel , de Castro José Adilson
Published: August 2012

The production of metallurgical coke and carbo chemicals generates residues that evaporate several persistent organic pollutants. Among them, the so-called BTX (benzene, toluene and xylene) are of special concern due to their accumulation into sources of vegetal and animal foods. Owing to the surface properties, large number of porosities and activated sites, activated carbon has been successfully used as a selective adsorbent material. In this study a theoretical model is proposed to analyze the rate of adsorption on the surface of activated carbon compacted produced from powders of micrometer size. The model considers the inner diffusion of BTX into the agglomerate particles. The model results confirm that the agglomerate produced by micro particles of activated carbon increases the amount of adsorption not only by the mechanism of surface action of the agglomerate but is enhanced by the gas diffusion into the pores and subsequent adsorption into the surfaces of the inner particles.
Morphological Characterization of UNCD on Etched <100> Silicon
Authors: Mengui Ursula A. , Ferreira N.G. , Baldan M.R. , Corat Evaldo Jose
Published: August 2012

We have proposed the growth of ultrananocrystalline diamond (UNCD) thin films on p-type (100) silicon etched with 27wt. % KOH in H2O. To get homogeneous distribution of micro pyramids on the silicon surface we have varied temperature (62 to 77 °C), etching time (1 to 35 min) and exposition diameter area (5 to 18 mm). For UNCD growth we have used hot filament chemical vapor deposition (HFCVD).The gas mixture have used 1 vol.% methane, 9 vol.% hydrogen and 90 vol.% argon, with the total flow rate of 200 sccm, at work pressure of 30 Torr. Images of Scanning Electron Microscopy (SEM) showed UNCD covered the silicon surface following the micro pyramidal morphology. Raman spectra (514.5 nm) showed all feature bands of UNCD such as: transpolyacethylene (1150 cm-1) and graphite (1350-1575 cm-1). The X-ray diffraction confirmed Raman spectroscopy. These results showed the silicon micro pyramidal structures obtained at 20 min, 75°C and 10 mm exposition diameter area as the more satisfactory for UNCD growth.
Physical and Chemical Characterization of Sorghum Bagasse
Authors: Miranda Mara Rúbia , Cardoso Cássia Regina , Ataíde Carlos Henrique
Published: August 2012

The steady rise in emissions from burning fossil fuels has caused increasing concern about their environmental impact. Lignocellulosic biomass can produce alternatives for gasoline and diesel by thermal conversion. Sorghum is used for animal feed since the feed value of its grain is similar to corn. The grain has more protein and fat than corn, but is lower in vitamin A. When compared with corn on a per pound basis grain sorghum feeding value ranges from 90% to nearly equal to corn. The grain is highly palatable to livestock, and intake seldom limits livestock productivity. Sorghum bagasse is the residue of sorghum after milling. The present work had the objective of characterizing sorghum bagasse for energetic use, especially to produce bio-oil by fast pyrolysis. The first step in pyrolysis process is the biomass characterization, since some kinds of particles are not suitable to be processed and need a previous preparation. For sorghum bagasse the performed physical analyses were: size distribution and medium diameter, and solids true density; the main chemical analyses were: ultimate analysis, proximate analysis, chemical composition and gross calorific value.
Size, Shape and Density Characterization of Tobacco Waste Particles
Authors: Cardoso Cássia Regina , Ataíde Carlos Henrique
Published: August 2012

There is an increasing concern about environmental problems associated with the rising emissions of CO2, NOxand SOxdue to the use of fossil fuels. Thus, renewable energy based on biomass could contribute to relieve the environmental and energy problems. Biomass energy conversion covers the processing of industrial and agricultural wastes, taking advantage of materials that would be discarded. In this work, tobacco residue characterization is studied; the material is a waste of tobacco industry. Values of true density were inferred for three different ranges of particle sizes and particles size and shape were studied for the three set of particles using dynamic digital image processing. The results show differences in physical characteristics of the biomass, varying the particle size.