bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Rhombohedral Graphite Phase on the Diamond Nucleation
Authors: Almeida Luciana Lezira Pereira , Skury Ana Lúcia Diegues , Monteiro Sérgio Neves , Bobrovinitchii Guerold Sergueevitch
Published: August 2012

The high pressure and temperature, synthesis of diamond from carbonaceous materials, is a complex process highly dependent on variables such as the catalyst/solvent, the crystalline structure of the precursor material, the processing conditions and the type of compressive chamber. The optimum susceptible precursors to be transformed into diamond are those possessing the perfect hexagonal graphite structure, which is the thermodynamically most stable form of carbon at atmospheric pressure and ambient temperature. However, the majority of both industrial and natural graphites, presents a mixture of different atomic structural arrangements that greatly influence the process of diamond synthesis. In this works the influence of rhombohedral and hexagonal phases existing in the graphite was performed by means of a software refinement of the crystal structures using the Rietveld method. The thermobaric treatment, which determine the structural parameters, was conducted in a high pressure anvil type device with a central concavity. All experiments were carried out at 1200°C and pressures varying from 4.3 to 5.0 GPa. It was determined that the degree of graphite to diamond transformation is directly associated with the content of rhombohedral phase.
Novel High Pressure Multi-Anvil Device for Diamond Production
Authors: Bobrovnitchii G.S. , Skury Ana Lúcia Diegues , Monteiro S.N.
Published: August 2012

The synthesis of diamond crystal from powder mixture of graphite and catalyst alloy is a well known process but it is limited to relatively small crystal dimensions due to the size of the conventional compression chambers. In this work the design and construction of a novel high pressure multi-anvil device with a parallelepiped shaped compression chamber is presented. The design allows the length of the chamber to be limited only by the working space of the press equipment. A four horizontal anvils device was constructed for a specific 2500 ton press with a 600mm working space. The efficiency of this construction was tested in diamond crystal synthesis.
Synthesis of ZrO2: ƞ wt% Re2O3 Powders by the Heterogeneous Coprecipitation Technique
Authors: Muñoz R.A. , Rodriguez J.E. , Silva Cosme Roberto Moreira
Published: August 2012

The zirconia in its cubic phase (C-ZrO2) has gained scientific and technological interest because it has high ionic conductivity and is useful in applications where the transport of oxygen ions prevails, for example, in the oxygen sensors and solid oxide fuel cells [1,. In the pure zirconia, the Zr4+ ion is too small to sustain the fluorite structure at low temperatures, so it has to be partially replaced by a higher atomic radius cation and lower valence number, for example, the Y3 +, Mg2 +, Ca2 + and the rare earth cations TR3 +, [. Currently there are several synthesis methods used to obtain cubic zirconia, the most popular being the mixture of oxides and coprecipitation used industrially in the research labs, but these methods provide powders with different characteristics which will be decisive for a specific application. In this context, the objective of this study was the preparation of homogeneous mixtures of zirconia-rare earth in different concentrations in order to stabilize the C-ZrO2, using the technique of heterogeneous coprecipitation for potential applications in oxygen sensors.
Analysis of the Hydroxyapatite Incorporate MTA Dental Application
Authors: Barros Criseuda Maria Benício , de Oliveira Sara Verusca , Marques Janaina Benício , de Souto Viana Kaline Melo , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

This research was incorporated the hydroxyapatite in a mineral trioxide aggregate sealer, with the aim of studying this influence in the structure, morphology and radiopacity of the cement to obtain osteoconductive material. The samples were characterized by X ray diffraction (XRD), spectrometry fluorescence X ray (EDX), spectroscopy transform infrared Fourier (FTIR), scanning electron microscopy (SEM) and radiographic appearance. Through the results obtained by XRD for the new sealer observed the formation of phases HAp and MTA evidenced by the presence of phases: CaO, SiO2and Bi2O verified also by EDX. Through FTIR was observed the presence of absorption bands related to links Ca-O, Si-O and Bi-O present in MTA and P-O present in HAp. The morphology visualized by SEM consists of irregular agglomerates with the formation of pre-sintered particles. The sample MTA/HAp3% presented radiopacity viable for their application as endodontic cement.
Evaluation of Calcined Temperature on the Structural and Morphological Characterization of TiO2 Doped with Zr Nanopowders Obtained by the Pechini Method
Authors: Ribeiro M.A. , Neiva Laédna Souto , Kiminami Ruth Herta Goldsmith Aliaga , de Oliveira J.B.L. , Gama L.
Published: August 2012

Because of the unique properties that the system TiO2-ZrO2 has, this system has attracted great interest in catalytic circles. In general, the TiO2-ZrO2 oxides composites have a greater surface area and a stronger acidity when compared to the single oxide and they are used as catalysts supports for many catalytic reactions. This work is to evaluate the effect of calcined temperature in structural and morphological characteristics of Ti1-xZrxO2nanopowders obtained by Pechini method. For this study, the doping value was 0.25 moles of Zr. The powders were calcined at temperature of 500 to 900°C for one hour. The powders were characterized by XRD, SEM and BET. The X-ray diffraction showed that the powders present a TiO2anatase phase and another of ZrO2tetragonal. The crystallite size ranged from 4.8 to 14.6 nm for the temperature of 500 to 900°C, respectively. The analysis of scanning electron microscopy showed soft homogeneous agglomerates with particles around 100 nm. The main particles sizes by BET were ranged from 10 to 20 nm, showing that the synthesis is effective to obtain nanometric powders.
One Domain Wall Hysteresis Model for Spherical Grain
Authors: de Campos Marcos Flavio , de Castro José Adilson
Published: August 2012

The high uniaxial magnetic anisotropy makes phases like Nd2Fe14B, Sm2Co17, SmCo5or BaFe12O19are very suitable as hard permanent magnetic materials. In the case of ferromagnetic materials, the global magnetostatic energy changes, according to the domain wall configuration. The simplest case to be studied is that of spherical grain with only one domain wall, in phases with uniaxial symmetry. The magnetostic energy in this system is calculated by means of Legendre polynomials. Studying the maximums and minimums of energy in this system, a simple hysteresis model can be developed. The model provides insight about the dependence of the coercive force on the grain size.
Influence of Addition of Chemically Treated Leather Shaving in the Portland Cement Mortars Characteristics
Authors: Ribeiro Daniel Véras , Yuan Shi Yung , Morelli Márcio Raymundo
Published: August 2012

The growing concern with environmental issues in tanneries and the search for a technological solution to their wastes are evaluated in this study. The waste named leather shaving was chemically treated aiming the immobilization of the chromium ion in a Portland cement paste, using mortars. 28 days-aged samples were evaluated in relation to their physical properties and axial compressive strength. Results showed that the alternatives used for the pretreatment were effective for the dissolution of the material, but they impaired the mechanical strength of samples.
Effect of Calcined Red Mud Addition on the Hydration of Portland Cement
Authors: Ribeiro Daniel Véras , Labrincha João A. , Morelli Márcio Raymundo
Published: August 2012

The red mud (RM) is a solid waste derived from the processing of bauxite ore to produce alumina and it is considered a hazardous waste due to its high pH. This paper describes the use of mud untreated and after calcination at distinct temperatures (450, 650, and 1000°C) attempting to improve its reactivity. The Portland cement was replaced up to 30 wt% red mud, and its addition changed the hydration process, evaluated by calorimetric studies of early hydration and setting time. By comparing with the reference mixture (without red mud), the obtained results confirm the potential of the red mud to be used as pozzolanic additive to cementitious materials. Temperature of hydration was monitored by a quasi-adiabatic calorimeter (Langavant). The hydration temperature increases with RM addition, particularly if calcined in the same interval (450-650°C). In this condition, the hydration process is accelerated.
Rheological Properties of a Sodium Bentonite and Lactose Aqueous Dispersion
Authors: Morais Leandro C. , Rosa A.H. , Fraceto L.F. , Toledo A.C.T. , Campos V.
Published: August 2012

Clay minerals, principally montmorillonites, offer a wide range of applications as adsorbent materials [1]. Clay layers in barriers may impede migration of toxic substances to the environment, in which case the effect of organic compounds on the particle-particle interaction and the mechanical stability of clay barriers must be considered [2]. The stability of band-like networks formed by partial overlapping of silicate layers and interlayer is affected by molecules and ions which are adsorbed on the external surfaces [3]. The evaluation of adsorbent materials effects can be done through viscosity measurements, in the present work some viscosity tests were done.
Silicon Carbide Surface Modification by Nitrogen Plasma Expander
Authors: Santos Carlos N. , Marins Eleasar M. , Machida Munemasa , de Campos Élson , Mota Rogério Pinto , de Melo Francisco Cristóvão Lourenço , Hein Luis R. Oliveira
Published: August 2012

Silicon carbide (SiC) has been employed in many different fields such as ballistic armor, thermal coating, high performance mirror substrate, semiconductors devices, among other things. Plasma application over the silicon carbide ceramics is relatively recent and it is able to promote relevant superficial modifications. Plasma expander was used in this work which was supplied by nitrogen and switched by a capacitor bank. Nitrogen plasma was applied over ceramic samples for 20 minutes, in a total medium of 1440 plasma pulses. SiC ceramics were produced by uniaxial pressing method (40 MPa) associated to isostatic pressing (300 MPa) and sintered at 1950°C under argon gas atmosphere. Silicon carbide (β-SiC - BF-12) supplied by HC-Starck and sintering additive (7.6% YAG - Yttrium Aluminum Garnet) were used in order to obtain the ceramics. Before and after the plasma application, the samples were characterized by SEM, AFM, contact angle and surface energy measurement.
CVD Diamond Films Growth on Silicon Nitride Inserts (Si3N4) with High Nucleation Density by Functionalization Seeding
Authors: Campos R.A. , Contin A. , Trava-Airoldi Vladimir J. , Moro J.R. , Barquete D.M. , Corat Evaldo Jose
Published: August 2012

Silicon Nitride is largely used as the base material to manufacture cutting tools. Due to its low thermal expansion coefficient it is ideal candidate for CVD diamond deposition. In this work, we functionalized the surface of silicon nitride inserts (Si3N4) with a polymer (PDDA Poly (diallyldimethylamonium chloride - Mw 40000)) to promote seeding with nanodiamond particles. The seeding was performed in water slurry containing 4 nm diamond particles dispersed by PSS Poly (sodium4-styrenesulfonate) polymer. CVD diamond films, with high nucleation density, were deposited in a hot filament reactor. Film morphology was characterized by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Diamond film quality was determined by Raman Spectroscopy. CVD diamond film adherence was evaluated using Rockwell C indentation.
Preparation of Organovermiculite for Adsorption of Organic Compounds
Authors: Silva Andréa Lopes , de Souza Francisco Kegenaldo Alves , Neves Gelmires Araújo , Menezes Romualdo Rodrigues , Lira Hélio Lucena , de Lima Santana Lisiane Navarro
Published: August 2012

Organically modified clay minerals are widely used as sorbents for hydrophobic organic compounds e.g., organic pollutants treatment from water solutions. Natural clay materials are hydrophilic and therefore they are not efficient sorbents for organic compounds. Intercalations of natural clay materials, with organic cations, with quaternary ammonium groups may become these clays hydrophobic. Vermiculite is the mineralogical name given to hydrated laminar magnesium-aluminum-iron silicate; this natural clay was modified and used for the production of organically modified clay (organovermiculite), with the purpose of its use in removing organic contaminants. The organovermiculite was prepared using different concentrations of distearyl dimethyl ammonium chloride (praepagen) based on cationic exchange capacity of the clay. It was evident from the X-ray diffraction that the salt was incorporated to the clay structure confirming its organophilization and through the Foster swelling test it was observed the affinity between the organic pollutants and the organovermiculite.
Study by Weibull Statistics of Ceramic Products from Rio Grande do Norte, Brazil
Authors: de Souza Tavares Elcio Correia , Cruz Claudia P.T. , Gomes Uilame Umbelino
Published: August 2012

The ceramic sector is important to the economy in Rio Grande do Norte, Brazil. Overall, however, the manufacturing process is imperfect; leading to inappropriate use of raw materials, waste of energy, environmental degradation, nonconformity to the Brazilian and international standards, etc. So, its crucial improves the produced bricks. This work aims to contribute to quality control of the ceramic industry, raising the values of physical properties of their products. The main parameters that influence these values were determined by Weibull statistics. Ceramics were studied by measuring porosity, water absorption, linear shrinkage, bulk density and mechanical strength. Mechanical strength test data resulted in Weibull distributions. The Weibull statistic parameter was calculated to best evaluations of ceramic quality. The results support our initial considerations about current stands of low quality of ceramic products from Rio Grande do Norte and underline the importance of testing and improving these products.
Modeling the Heat Treatment of Dy-Diffused Nd2Fe14B Magnets: The Shell Model
Authors: de Campos Marcos Flavio , de Castro José Adilson
Published: August 2012

In Nd2Fe14B sintered magnets there is increase of coercivity after Dy diffusion in the region near the surface of the grains. A kinetical model evaluating the Dy surface diffusion is presented. This model is based on a shell hypothesis: the most relevant place for the nucleation is a tiny shell near the grain boundaries. The kinetical analysis shows that a heat treatment during 1 hour at 850°C is able to produce a Dy-rich layer on the surface of the Nd2Fe14B grains.
Influence of Exchanged Surfactant on the Structure and Adsorption Properties of Brazilian Green Mud Clay
Authors: Mota Mariaugusta Ferreira , Machado Fabricio , Freire Rodrigues Meiry Glaúcia
Published: August 2012

This work presents an experimental study focusing on the preparation and characterization of modified natural green clay-mud with quaternary ammonium salts of chloride and alkyl dimethyl benzyl ammonium chloride (Dodigen) and dimethyl stearyl ammonium chloride (Praepagen). X ray Diffraction (XRD), infrared spectroscopy (IR) and expansion tests (adsorption capacity and Foster swelling) measurements were performed in order to evaluate the performance of the ion exchange reactions and the degree of affinity with oil products. It is observed an increasing in the XRD basal spacing of the modified clays (1.96 nm and 2.25 nm for Praepagen and Dodigen salts, respectively) in comparison to the observed value (1.56 nm) for the natural clay. The IR results showed that salts were successfully incorporated to natural clay structure. Based on the expansion tests the organoclays presented the best efficiency independent on the kind of solvent used in comparison with the natural clay performance.
Porous Anisotropic Alumina Ceramic Membrane: Preparation and Characterization
Authors: Cordeiro Valéria Vital , da Silva Mirele Costa , Lira Hélio Lucena , de Freitas Normanda Lino , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

Through different field of application and productive growth that membrane technology has been presented in the last years, the aim of this work is to prepare and characterize anisotropic porous ceramic membrane. The membrane were done with alumina, prepared by combustion reaction in microwave oven from urea as combustible and after deposited on support based on a commercial alumina. The results showed that it was obtained α-alumina as unique phase with average agglomerate size of 10µ and surface area of 33 m2/g. The alumina morphology was constituted by pre-sintering particles with hard agglomerates and/or aggregates. In relation to the membranes, it was observed a longitudinal section without cracks and uncovers support surface, also it can be observed grain formation well distributed and a layer of alumina with approximately 35.25µm. In relation to the permeate flux, the membrane presented initially values relatively high that is decrease with the permeation time, due to adsorption of water in the internal surface of the pores of the membrane, experiencing a decrease in size.
Transition Metals in Glass Formation
Authors: da Silva Antônio Carlos , Santos S.C. , de Mello-Castanho Sonia Regina Homem
Published: August 2012

The structure of silicate glasses gets its charge stability through SiO2, R2O3, R2+and R+groups arrangement. In these glassy structures, transition metals are usually used as dopants in small amounts. However, in soda-lime glass systems, transition metals can take part in the glassy network in larger quantities as secundary former or modifier, insted R2+groups, if the charge balance conditions are made favorable by R2O3groups additions. This paper studies transition metals (Cr, Ni, Fe, Cu, Zn, Pb, Ru) soda-lime-borosilicate glass network incorporation. This process was applied for many kinds of toxic metals containing vitrification waste. The glasses were obtaind by melt at temperature of 1300°C, and characterized by FT-IR and XRD techinics. The chemical stability was evaluated by hydrolytic attack test. The glasses showed a high chemistry and environmental stability like the soda-lime glass.Keywords: glass structure, electroplating waste, e-waste, nanowaste.
Alumina Residue Characterization to Produce Tubular Ceramic Membranes
Authors: Oliveira Guimarães Iliana , Lira Hélio Lucena , da Silva Sidinei Kleber , Dias Suellen Lisboa , de Oliveira Lima Rosa do Carmo
Published: August 2012

ndustrial wastes recycling become attractive due to raw materials economy (sustainability) and environmental issues. This research objective was to characterize a residue generated during the alumina calcination process (electrostatic precipitator dust), to be applied on the development of tubular ceramic membranes. In this context, two samples were analyzed, a crude residue (sample A) as supplied by the industry and other calcined residue (sample B). As verified by X-ray fluorescence spectroscopy by dispersive energy (XDE), the samples A and B showed a high content of alumina in chemical compositions, both close to 96%. Gibbsite and α-alumina crystalline phases were identified by X-ray diffraction (XRD) in the samples. At scanning electron microscopy (SEM) images, could be observed agglomerates of particles with asymmetric shapes and a wide particle size distribution like was confirmed by laser diffraction, which showed that the particles diameters remained almost unchanged after calcination at 700°C. Results revealed no significant differences between samples characteristics, indicating that the crude and calcined residues could be used to prepare ceramic membranes.
Use of Calcined Tannery Sludge Containing Chromium Compounds in Soda-Lime Glass Fabrication
Authors: Chambi M.M. , Toffoli Samuel Marcio
Published: August 2012

Tanning industries generates large quantities of solid wastes containing chromium compounds with characteristics of high-polluting and hazardous conditions. However, these wastes are a potential source of chromium which could be used by the glass and ceramic enamels industries. In this study the properties of a calcined tannery sludge containing chromium compounds was investigated in order to evaluate the potential of using this powder as a suitable and cheap green colorant for the glass manufacturing. X-ray diffraction (XRD), chemical (XRF) and thermal (DTA/TG) analyses were used to determine the physical and chemical characteristics of tannery sludge. Colorimetric method using diphenylcarbazide were conducted to determinate the Cr (VI) concentration in the samples. Soda-lime glass containing calcined tannery sludge was prepared by melting at 1550°C. The results showed that the calcined tannery sludge has a favorable behavior to be used as an alternative source of chromium for the glass manufacturing.
A General Coercivity Model for Soft Magnetic Materials
Authors: de Campos Marcos Flavio
Published: August 2012

The effect of crystalline imperfections (as for instance, grain size, inclusions and dislocations) on the coercivity of soft magnetic materials is additive. This only can be explained by an Energy Balance Model. By another hand, the angular dependence of the coercivity only can be explained with a Force Balance Model. Thus both models, Energy Balance and Force Balance have to be invoked for the construction of a general model. The effect of dislocations on the coercivity can be treated as short range magnetostrictive effect. The effect of inclusions needs the consideration of the global magnetostatic energy of the system. The dependence of the coercivity with the grain size can also be explained analyzing the magnetostatic energy. The idea of pinning of domain walls by crystalline defects is reformulated, and it is shown that the coercivity increase due to crystalline defects is principally caused by variations of the magnetostatic energy in the system.
Characterization of Industrial Wastes, Glass and Ceramic Wool
Authors: Evangelista Neuza , Tenório Jorge Alberto Soares , Oliveira José Roberto , Borges Paulo R. , Ferreira Taiany Coura M.
Published: August 2012

Ceramic fibers are characterized by their light weight, high degree of purity, low heat storage, low thermal conductivity, thermal shock resistance and superior corrosion resistance in high-temperature environments. In addition, they can be produced extensively in substitution to all materials used in the coating of almost all heating equipment as well as contributing to the reduction of energy consumption. Such characteristics make them ideal in the coating of distributors, mufflers, heating ovens, among others, as highly demanded by the mining and metallurgical industries, among others. After use in the process of industrial production, generated waste will lose their insulation capacity and thus require safe disposal. The present work focuses specifically on ceramic and glass wools aiming at an evaluation of their recycling prospect of incorporation into cement mortars and concrete. This residues were pulverized and displayed ~30µm average particle size. The scan electronic microscopy (SEM) presented elongated, thin and straight particles, which is very different than flocular structure of cement. The X-rays diffraction revealed amorphous structure for glass wool and crystalline structure for ceramics wool. The chemical analysis showed high concentrations of Al2O3 and silica in both residues, with higher percentage of calcium oxide in glass wool.
Effect of Surface Properties on Particle Growth Kinetics for Polymer Coating in Spouted Bed
Authors: Matheus Boeira Braga , Sandra Cristina dos Santos Rocha
Published: August 2012

In this research, glass beads with size range between 1.68 and 2mm were coated with 5 polymeric suspensions. The suspensions formulations differ in relation to their employment and physical properties (solids concentration, surface tension and rheology), generating different characteristics of wettability and adhesion with the nucleus. The aim of this study was to evaluate particle coating in a spouted bed through analysis of particle growth in terms of solid surface energy, wettability, and adhesion before and after the formation of the first layer of polymeric film on the particle. The solid-suspension and film-suspension systems were characterized by contact angle and surface energy. The operating conditions were fixed for all suspensions: 1.5 kg of beads, air velocity of 0.369 m/s, air temperature of 60 °C, suspension flow rate of 4 ml and atomizing pressure of 10 psig. Analyzing particle growth kinetics, different behaviors were observed and related not only to glass-suspension wettability, but also to polymeric film-suspension surface properties.
Study of Titanium Surface Topography Influence on Biomimetic Coating Deposition
Authors: Balestra Roseli Marins , Ribeiro Alexandre Antunes , Andrade M.C. , Pereira Luiz Carlos , Varella Marize
Published: August 2012

Studies show that calcium phosphate coatings on titanium implants improve osseointegration at the implant-bone interface, due to the mineral biocompatibility. Titanium implants can be coated with calcium phosphates by a biomimetic precipitation method. This work studied a biomimetic method under a simplified solution with calcium and phosphorus ions. As substrates, commercially dense titanium sheet and macroporous titanium samples produced by powder metallurgy were used, both ASTM F67 grade 2. The substrates were submitted to chemical and heat treatment and then immersed in the solution for 10 days. Samples characterization was performed by Optical Microscopy (OM), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS), low angle X-ray Diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Powder metallurgy successfully produced macroporous titanium substrates. Calcium phosphate coatings were deposited on both substrates, confirmed by FTIR bands. Such results indicated the potential of this methodology for calcium phosphate coatings on titanium substrates.
Modeling of the Fischer-Tropsch Synthesis Aiming to Predict the Production of Paraffins and Olefins
Authors: Ventura Danilo Alencar Mayer Feitosa , dos Santos Monaysa Kelly Valadares Araujo , Alves José Jailson Nicácio , Neto Antônio Tavernard Pereira , de Sousa Bianca Viana
Published: August 2012

The growing concern with the global environmental issues has resulted in a constant demand for the production of clean fuels. Therefore, researches were carried out in order to improve the gas-to-liquids technology, well represented by the Fischer-Tropsch synthesis. This synthesis is able to produce liquid fuels from syngas, a mixture of carbon monoxide and hydrogen which is obtained through the processing of the methane gas. Based on literature data, this paper suggests a kinetic model developed by making use of the Matlab® commercial application. The goal was to predict the production of hydrocarbons such as paraffins and olefins with up to six carbons in each chain. The Fischer-Tropsch synthesis was conducted with the catalyst 20% Co/ MCM-41 in fixed bed reactor at the temperature of 270 °C and atmospheric pressure. The results obtained by the model for both paraffins and olefins were compared with experimental data found in the literature.
Containerless Solidification of Eutectic PbSn Alloy Droplets in a Drop Tube
Authors: Toledo Rafael Cardoso , de Freitas F.E. , An Chen Y. , Bandeira I.N.
Published: August 2012

Containerless solidification of 300 to 850 µm diameter droplets of PbSn eutectic alloy was achieved by using a 3m length drop tube, which is one of the most suitable and low cost option to provide a microgravity environment on the ground. Phase morphology and composition were investigated, respectively, by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). It was found that the microstructure of the droplets depends on their sizes, where in larger diameters (>500µm) consists of both regular lamellar and irregular structures, and on other hand, for the smaller ones (<500µm) the structure is only irregular with higher lead concentration.
The Influence of the Operating Parameters of Titanium Electropolishing to Obtain Nanostructured Titanium Surfaces
Authors: Antonini Leonardo Marasca , Mielczarski Rafael Gomes , Pigatto Caroline , Müller Iduvirges Lourdes , Malfatti Célia de Fraga
Published: August 2012

Titanium and Ti alloys have been widely used as biomaterial due to their mechanical properties and high in vitro and in vivo cytocompatibility. Studies have showed that the acceleration of the osseointegration process is associated to the modification of the surface morphology. The aim of this work is to study the influence of the operating parameters of titanium electropolishing to obtain nanostructured titanium surfaces. The titanium electropolishing was carried out with different temperatures (7°C, 18°C and 25°C), current density of 0.19 A/cm2 and electropolishing time of 8 minutes. After the electropolishing process the titanium samples were characterized by Atomic Force Microscopy, profilometry (mechanical profilometer) and contact angle measurements. Preliminary results showed that the Ti nanostructured surfaces formation, strongly depends on the control of operating parameters.
Study of the Influence of Different Synthesis Conditions of PANI-HF in its Property as Ammonia Gas Sensor
Authors: Duarte Glaucea Warmeling , Tachinski C.G. , Naspolini A.M. , Consenso E.C. , Silveira F.Z. , Riella Humberto Gracher , Fiori M.A.
Published: August 2012

ntrinsically Conducting Polymers (ICPs) are of increasing interest, especially in areas such as electronic devices. PANI is one of the most intensively investigated of the ICPs due to its easy chemical synthesis, easy doping process by protonic acids and also because it is chemically stable at room temperature conditions. PANI is used as sensor for many gases that are responsive for air pollution The applicability of these materials as sensors is based on their selectivity over a wide range of analyte molecules and low level of gas concentration, the potential to operate at or near room temperature and also its response time. The present work studies the influence of different synthesis conditions of PANI-HF in its electrical resistance when subjected to the presence of ammonia gas. The PANI-HF was chemically synthesized and it was submitted to electrical and physical characterization. The preview results showed that the synthesis conditions change significantly the response of PANI-HF to ammonia gas.
Determination of the Chemical and Mineralogical Composition of Drilled Cuttings at Different Points throughout the Solids Control Process
Authors: Pereira Marina Seixas , Panisset C.M.A. , Lima T.B. , Ataíde Carlos Henrique
Published: August 2012

In this work, we use x-ray fluorescence and x-ray diffraction methods to investigate the chemical and mineralogical composition of drilled cuttings at different points throughout the solids control process. Cuttings coated or contaminated with drilling fluid are the result of drilling. Over the past twenty years, studies have been conducted to assess the effects that these contaminated cuttings have on the environment, in both offshore and onshore scenarios. A more restrictive environmental legislation and the need to reduce drilling costs (exploration and production) has led to the optimization of solid-liquid separation. Knowledge of the chemical and mineralogical composition of drilled cuttings will assist in finding a dispersant and in determining an appropriate procedure for carrying out particle size analysis of these solids.
Effect of Ornamental Rock Sludge on the Strength and Densification of Cement Pavement Blocks
Authors: Bahiense A.V. , Alexandre J. , Vieira C.M.F. , Monteiro S.N.
Published: August 2012

The city of Cachoeiro de Itapemirim, in the southwest of Brazil, has a large industrial activity related to the extraction of ornamental stones. This brings jobs and income to the state of Espirito Santo but also cause problems due to the discard of the sludge resulting from the stone processing operations (SPO). The reuse of this SPO in construction materials such as plaster and bricks has been proposed as an alternative to reduce its environmental impact. This work evaluates another low cost alternative based on the incorporation of the SPO in the fabrication of cement pavement blocks. Using an experimental planning method, the mixture of sand, gravel and SPO, jointly with a water/cement proportion, was investigated for the method surface response. Based on this statistical method, pavement blocks with an apparent density of 1.96 g/cm3were found for incorporation in the range of 10 to 34%.
Process Variable Influence on Fertilizer Drum Granulation Performance
Authors: Rodrigues Rafaella F. , Leite Sergio , Oliveira Juliana G. , Ataíde Carlos Henrique , Barrozo Marcos A.S.
Published: August 2012

The main purpose of this study was to determine the influence of process variables on granulation of ordinary super phosphate. The experiments were performed in a drum with an internal volume of 25 l and the evaluated variables were rotation speed, liquid phase, granulation time and fill level of the drum granulator. Central Composite Design (CCD) was used to choose the experimental conditions. The correlation between data and process variables was established using Multiple Regression. The granulation products were analyzed using standard separators and the Haver CPA photo-optical particle size measurement system. The tendency toward granulation and formation of coarse or fines could be predicted according to the specific surface of the granulation product and the granulation size distribution was found to be greatly dependent on the variable studies.
Nanoparticles of Carbonaceous Minerals in Vulcanized Rubber Products
Authors: Martín-Cortés Guillermo Ruperto , Esper Fabio José , Hennies Wildor Theodoro , Tomi Giorgio , Valenzuela-Díaz Francisco Rolando
Published: August 2012

The use of vulcanized rubber products is widely spread in the industry and in the society. Tires, shoes, tennis and other are examples of it. Most of the raw materials used in the formulations of vulcanized rubber products come from the synthesis of natural raw materials consuming time and energy and also generating CO2 emissions during the respective transforming processes. The main reinforcing material used in rubber formulations is the carbon-black which is a petroleum derivative obtained by the incomplete burning of the fossil fuel. This paper show some results obtained after replacing all or part of the carbon-black by carbonaceous nanoparticle minerals in rubber formulations.
Modeling the Densification of FeSi Sintered Magnetic Alloys
Authors: de Castro José Adilson , Concilio Gilberto V. , Rodrigues Daniel , Santomauro Livia S. , de Campos Marcos Flavio
Published: August 2012

An important process parameter in FeSi sintered alloys is the sintering temperature. If the sintering temperature can be reduced, the sintering process could be performed in less expensive furnaces. A densification model is here applied to experimental data. The model considers both grain size and density. After the model is applied to experimental data, the acquired model parameters allow the simulation of densification for other situations of temperature and heating rates. The model can be helpful to find suitable sintering temperatures in these alloys.
Mechanical Properties and Abrasive Behavior of Diamond Incorporated Epoxy Composites
Authors: Amaral Camila Rodrigues , Rodríguez Rubén Jesus Sánchez , Junior Lucivan P.B. , Skury Ana Lúcia Diegues , Monteiro Sérgio Neves
Published: August 2012

The thermal and mechanical properties assessed respectively by dynamic mechanical analysis and flexural bend tests as well as the abrasive behavior obtained by wear tests of diamond particles incorporated epoxy matrix composites were investigated. Diamond particles with sizes in the range of 45 to 115 µm, synthesized at high pressure and temperature, were mixed in amounts of 20 and 40 wt% with dyglycidyl of the bisphenol A, DGEBA, epoxy resin cured with stoichiometric ratio of tetraetylenepentamine, TEPA, hardener. These composites were dynamic mechanical, DMA analyzed and three points bend tested. The behavior of the composites as abrasive tool for industrial polishing of ornamental rocks was evaluated by wear tests. The results showed an improved performance of the DGEBA/TEPA composites with incorporation of diamond particles.
Preparation of UHMWPE/MMT Nanocomposites via Mechanical Alloying
Authors: de Lima Carlos Alberto Silva , Cintho Osvaldo Mitsuyuki , de Melo Carvalho Benjamim
Published: August 2012

The ultra high molecular weight polyethylene (UHMWPE) has a molecular mass of the order of a millions of grams per mole. So, UHMWPE presents prominent properties, for instance, abrasion and impact resistance. However, due to its very high viscosity in the melt state, the preparation of composites by conventional extrusion and injection molding is not possible. Therefore, in this work we studied the possibility of incorporating montmorillonite (MMT) into the matrix of the UHMWPE in the solid state, via high energy milling. The formulations were prepared in Attritor mill by milling UHMWPE reactor powder and MMT. The samples were characterized by bulk density, XRD, AFM and SEM. Results show that this route of processing was effective to incorporate MMT into the matrix of UHMWPE.
Influence of Bentonite Clay Content in HDPE Nanocomposites
Authors: de Oliveira Sara Verusca , Costa da Silva Milena , Brito Gustavo Figueiredo , de Lima Antônio Gilson Barbosa , Araújo Edcleide Maria
Published: August 2012

This research is to obtain nanocomposites of HDPE/bentonite clay. Inorganic polymers reinforced with materials are of great interest due to their applications in automotive, and electrical and electronic industries. The nanocomposites were produced by melt intercalation with different percentages of clay and compared with pure HDPE. Clay was used as modified and unmodified and it was characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF). The obtained nanocomposites were characterized through thermogravimetry (TG). It was verified by XRF that clay performed compositions of bentonites characteristics. By XRD, it was observed increases basal spacing for organoclay. By TG, in general, it was verified that the nanocomposites presented greater thermal stability in relation to HDPE.
Modeling of the Height of Sediment in a Continuous Thickener
Authors: Lira J.R. , Arouca Fábio de Oliveira , Damasceno João Jorge Ribeiro , Oliveira-Lopes L.C.
Published: August 2012

Mathematical models for thickeners can be used for equipment design, to simulate the process operation, and to develop control strategies for a continuous operation. In this work, numerical simulation to obtain the final height of the sediment when operating at steady state conditions were performed using two mathematical models: the model introduced by Tiller and Chen (1988) and the one proposed by Arouca (2007). The simulated results were compared to experimental data obtained when the thickener was operated with and without the use of flocculent agent. The equipment used to obtain experimental data was a conventional thickener, built in acrylic. Aluminum sulfate was used in the experiments for the production of flocculated suspensions. The results showed that the Tiller and Chen (1988) model produced a deviation of 39.0% for kaolin suspensions and 14.3% when aluminum sulfate was added to the system. The Arouca (2007) model resulted in values much closer to those obtained experimentally, with deviations of less than 3% for kaolin suspensions regardless of the use of flocculent agent.
Experimental Analysis of Heat Transfer inside Packed Beds of Soybean Seeds
Authors: Souza G.F.M.V. , Béttega R. , Miranda R.F. , Mendoza O.S.H. , Barrozo M.A.S.
Published: August 2012

Several applications in chemical industry use randomly packed bed of particles, such as particulate separation systems, chemical reactors or fixed bed drying. Fluid dynamic behavior, heat and mass transfer, in addition to structural properties of the bed are fundamental issues to design of these processes. Several studies about heat transfer in packed beds aiming drying application have been performed in order to contribute with the process. Seeds drying temperature is especially important for the seeds quality indices and must be carefully controlled in drying process. In this paper temperature profiles experimentally obtained in a packed bed composed by soybean seeds are presented and discussed. Axial profiles of temperature were applied for obtaining effective thermal conductivity following previous studies from literature. The results indicate that thermal homogeneity can be achieved inside the bed for controlled air flow conditions. Axial effective thermal conductivity presented results in agreement with previous studies from literature.
Isoconversional Kinetic Analysis of Pyrolysis of Sugarcane Bagasse
Authors: dos Santos Kássia Graciele , Malagoni Ricardo A. , Lira Taisa S. , Murata Valéria V. , Barrozo Marcos A.S.
Published: August 2012

This paper presents a kinetic study of pyrolysis of sugarcane bagasse from dynamic thermogravimetric experiments (TG). The methods of Kissinger, Ozawa, Starink, Kissinger-Akahira-Sunose and Friedman were used to estimate the activation energy. These methods consider the temperature shifts with increase of heating rate for a given conversion in dynamic TG tests. The activation energy values obtained by the isoconversional methods were in a range 182.8 192.4 kJ·mol-1, values very close to the other biomasses presented by literature.
Obtaining of Polymer Films from Nylon 6/Bentonite Clay Nanocomposites: Structural Characterization
Authors: de Gouveia Silva Taciana Regina , Medeiros Keila Machado , Menezes Patrícia Costa Fernandes , Araújo Edcleide Maria , de Mélo Tomás Jefférson Alves
Published: August 2012

The nanocomposites are hybrid materials where at least one of the components has nanometric dimensions and in the same way as traditional composites are formed, one of the components is the matrix in which nanoparticles are dispersed. One of the possibilities of applications of nanocomposites is to obtain polymer films for applications in the barrier, or separation promoted by the dispersion of the clay lamellae. In this work, nanocomposites of nylon 6/bentonite clay were obtained by melt intercalation. The used clay was the Brasgel PA, and quaternary ammonium salt was Praepagen-HY, used in organophilization of the clay. By XRD, it was observed the disappearance of the characteristic peak of clay, and this can be facilitate the possible exfoliation of clay in the produced films from the nanocomposite. By SEM, it was observed, an apparently dense layer with no pores.
Analysis of the Influence of Mini-Pipes Diameter in the Performance of a Non-Conventional Rotary Dryer
Authors: Silvério Beatriz Cristina , Soares A.C.C. , Arruda E.B. , Duarte Claudio Roberto , Barrozo Marcos A.S.
Published: August 2012

Conventional rotary dryers are used in many industrial sectors. The present work analyzes the drying of granulated fertilizers in a non-conventional dryer. The major characteristic of this new dryer is the presence of an aerated system consisting of a central pipe from which a series of mini-pipes conduct the hot air directly to the particle bed that is flowing at the bottom. This work has tested several diameters of mini pipes and the better experimental results were obtained with mini pipes of 9 mm.
Study of Obtainment of NiCrAlC Alloys by High Energy Ball Milling
Authors: Pereira Joéverton I. , da Silva Alisson K. , Vurobi Jr. Selauco , Capochi José Deodoro Trani , Cintho Osvaldo Mitsuyuki
Published: August 2012

This work aims the synthesis of nickel alloys (Ni-Cr-Al-C) with different amounts of carbon, in order to measure the hardness and analyze the chromium carbides distribution and size, as well as for gamma prime phase. It has been used the mechanical alloying technique in order to provide a fine dispersion of chromium carbides in the gamma prime phase matrix. The materials were characterized by x-ray diffraction, differential scanning calorimetry, scanning electron microscopy, energy dispersion spectroscopy, and microhardness test.
Granulometric Characterization of Flotation Products
Authors: Santana R.C. , Santos M.A. , Santos T.C.M. , Souza T.A.A. , Ataíde Carlos Henrique , Barrozo Marcos A.S.
Published: August 2012

This work aimed on the granulometric characterization of flotation products and to analyze the effect of the variables (that were investigated in a flotation work) on the particle size distribution parameters. Besides to compare the parameter values of the granulometric analysis for the concentrate and tailing both results were compared with the parameter values of the flotation feed samples. The analyzed parameters showed lower values for the concentrate products as compared with the parameters for tailing and feed samples. For coarse and fine particle size fractions the column height was the variable that more influenced on the parameter values.
Synthesis, Characterization and Thermal Properties of an Europium (III) Nanocomplex
Authors: Silva H.C. , da Silva Morais Crislene Rodrigues , Morais S.A. , Lira B.F.
Published: August 2012

The coordination of lanthanide íons with organic ligands has provided good luminescent properties and allows its application in molecular light converter devices, which motivates the scientific interest of seeking coordination of these íons with organic ligands that potentiate the luminescence and associate biological properties of the complexes formed. From this perspective the complex was synthesized Eu (III) with mesoionic 2(4-chlorophenyl)-3-methyl (methoxyphenyl)-1,3-thiazole-5-thiolate (MS-1) and bipy, with the aim of its possible application in the areas of photoluminescence and drug. Analyses were performed using TG, DSC, XRD and IR. The complex obtained after reaction of the lanthanide salt and organic ligands showed five stages of decomposition and different fusion of the isolated ligands.
Residual Stresses Measurements Using Strain Gages - Aluminum Wheels
Authors: Cione F.C. , Rossi J.L. , Souza A.C. , Delijaicov S. , Colosio M.A.
Published: August 2012

Many engineering specifications, manufacturing procedures, inspection and quality control have begun to require that the residual stress of a particular component be evaluated. This is becoming as commonplace as the demands on the mechanical properties. In the country there are few research laboratories qualified to perform these tests and also found a worrying lack of skilled labor. Studying the formation and distribution of residual stress fields will improve the operational criteria of wheel safety, among other gains. It is known that these residual stress fields could be added to the effects of system load (tare weight plus occupation of vehicle traction, braking and torque combined). The results obtained used drilling method and rosette type strain gages, are convergent with similarity to those obtained using FEA simulation over critical region for global and superficial in principal stresses mode. The relevance of the present study and research on residual stresses meets safety improvements in cars wheel industry.