bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Polymer/Nanoceramic Composite Material with Potential Application in Biomedical Engineering
Authors: Santos Diego Vieira , Casadei Ana Paula Marzagão , Pereira R.V. , Aragones A. , Salmoria G.V. , Fredel M.F.
Published: August 2012

The rise of human life expectancy results in the increasing of elderly population and consequently the diseases of old age, which are mostly related with bone degenerative diseases. These problems also affect young individuals, commonly due to accidents (automobile and work). This fact has stimulated the research and development of materials that can replace or regenerate the damaged bone. From the engineering view, bone is a composite material consisting of an organic matrix (collagen), reinforced by an inorganic component (hydroxyapatite). The search for a suitable material, with properties tailored to the needs of the bone metabolism, as well as the adequate way of material processing, which ensures the maintenance or improvement of their initial properties, motivated this research. In this work was developed composite materials, based on bioresorbable polymer (PLLA) and phosphocalcic nanoceramic (HA). The composites were characterized by scanning electron microscopy (microstructure) and dynamical mechanical analyses (mechanical behavior). The results indicated these materials as promising for applications in the medical and dental manufacturing devices (plates and screws) by injection molding, and also for scaffolds by rapid manufacturing, in the tissue engineering area.
Preparation of Al2TiO5-Al2O3 and Al2TiO5-Al2O3-TiO2 Ceramics by High-Energy Ball Milling and Sintering
Authors: de Oliveira Caltabiano Pietro Carelli Reis , de Souza Marisa Aparecida , Marques Rodrigo Fernando Costa , Campos Maria Gabriela Nogueira , de Oliveira Hein Luis Rogério , Ramos Alfeu Saraiva
Published: August 2012

The present work reports on the preparation of Al2O3-TiO2 ceramics by high-energy ball milling and sintering, varying the molar fraction in 1:1 and 3:1. The powder mixtures were processed in a planetary Fritsch P-5 ball mill using silicon nitride balls (10 mm diameter) and vials (225 mL), rotary speed of 250 rpm and a ball-to-powder weight ratio of 5:1. Samples were collected into the vial after different milling times. The milled powders were uniaxially compacted and sintered at 1300 and 1500°C for 4h. The milled and sintered materials were characterized by X-ray diffraction and electron scanning microscopy (SEM). Results indicated that the intensity of Al2O3 and TiO2 peaks were reduced for longer milling times, suggesting that nanosized particles can be achieved. The densification of Al2O3-TiO2 ceramics was higher than 98% over the relative density in samples sintered at 1500°C for 4h, which presented the formation of Al2TiO5.
Study of the Spheronization Process of Glass Particles for Internal Selective Radiotherapy Application
Authors: Barros F E.C. , Sene F.F. , Martinelli J.R.
Published: August 2012

The selective internal radiotherapy is an alternative to treat hepatocellular carcinoma. Glass microspheres containing a β-emitter radionuclide are introduced in the liver, and they concentrate preferentially in the region where the cancer cells are located. The microspheres are trapped in the arterioles which feed the tumors, and the β-particles annihilate the cancer cells. The glass particles must be spherical to avoid unnecessary bleeding, and the particle size must be restricted to a range which optimizes the blocking effect. Glass microspheres can be produced by heating glass particles using a flame or in a hot zone of a furnace. The particle size distribution is not easily predicted since it depends on the variation of the aspect ratio and the presence of agglomerates. In the present work, the spheronization process to obtain microspheres with diameters appropriate for radiotherapy treatment is evaluated. Samples were characterized by X-rays diffraction and Energy Dispersive X-rays Fluorescence Spectroscopy. The glass dissolution rate was determined in water at 90°C, and in Simulated Body Fluid (SBF) at 37°C. Glasses with dissolution rates close to 10-8g/(cm2.d) were obtained, which make them suitable for the present application. Scanning Electron Microscopy was used to evaluate the surface of the microspheres before and after the dissolution tests.
Subcritical Crack Growth Velocities (v-K Curves) of Dental Bioceramics
Authors: Yoshimura Humberto Naoyuki , Gonzaga Carla Cristina , Cesar Paulo Francisco , Miranda Walter Gomes
Published: August 2012

In this study the subcritical crack growth (SCG) behaviors of five dental bioceramics were evaluated in order to plot the crack growth velocity versus stress intensity factor (v-K) curves. Disc-shaped samples of two sintered porcelains, two glass-ceramics, and a glass-infiltrated ceramic composite were prepared and tested in artificial saliva using a biaxial flexure jig. The SCG parameters were evaluated by the dynamic fatigue test using five constant stress-rates and in an inert condition. Among the tested materials, the lithium disilicate glass-ceramic showed the highest susceptibility to strength degradation by SCG, whereas the glass infiltrated alumina composite showed the lowest susceptibility. The v-K curves showed that the SCG susceptibility significantly affects the crack growth velocity of the different bioceramics.
Influence of Preparation Method of the CeO2 over their Structural Characteristics
Authors: Neiva Laédna Souto , Simões Aluska N. , Oliveira Matheus J.C. , Ribeiro Maria Aparecida , Leal Elvia , Gama Lucianna
Published: August 2012

The aim this work is to synthesize the CeO2in the ceramic powder form through three different methods of synthesis, they are: method of combustion, Pechini method and hydrothermal method. Will be evaluated the influence exerted by these methods of preparing of the metallic oxide on the structural features presented in the same. Three samples of CeO2were synthesized in this work, they were analysed by x-ray diffraction, SEM and adsorption and desorption of N2by BET method. According to the results has been observed that the synthesis method has great influence on the structural characteristics of CeO2obtained. The sample of CeO2synthesized by Pechini method showed a structure with a higher percentage of crystallinity and average pore diameter smaller when compared to samples of CeO2synthesized by means of the combustion method and of the hydrothermal method. The sample synthesized by the combustion reaction method presented larger agglomerated of unitary particles.
Synthesis of ZnAl2O4 Catalytic Support by Combustion Reaction Using Different Fuels
Authors: Leal Elvia , Dantas Bruno Brito , Neiva Laédna Souto , Kiminami Ruth Herta Goldsmith Aliaga , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

This work shows the influence of the fuels aniline, carbohydrazide and glycine on structural and morphological characteristics of ZnAl2O4synthesized by combustion reaction. Samples were prepared according to the propellants and explosives theory using a vitreous silica crucible and a muffle furnace as heating source. During the synthesis was measured the time and temperature of the reaction. After The samples were structurally and morphologically characterized by the following techniques: XRD, nitrogen adsorption / desorption (BET / BJH), and SEM. The higher temperature was achieved by the synthesis using aniline, whose value was of 876°C. XRD results showed that all the samples presented the ZnAl2O4spinel as majority phase and, ZnO and Al2O3as segregated phases. The samples also showed low surface area, varying of 23.6 to 28.7 m2/g, and particle size of 45 to 55 nm, besides mesoporous characteristic and irregular agglomerates formation.
Influence of Citric Acid/Metallic Cations Ratio in the Structure, Morphology and Photocatalytic Activity of TiO2 Prepared by Pechini Method
Authors: Ribeiro P.C. , de Melo Costa Ana Cristina Figueiredo , Sasaki J.M. , Kiminami Ruth Herta Goldsmith Aliaga , Lira Hélio Lucena
Published: August 2012

This aim of this work is to evaluate the influence of citric acid/metallic cation ratio of 3:1, 4:1 and 5:1 used in the TiO2synthesis by Pechini method in the structure, morphology and photocatalytic activity of methyl red dye. The prepared samples were characterized by X-ray Diffraction (XRD) using Rietveld refinement method, textural analyses, and photocatalytic activity. The results obtained by XRD technique confirm the efficiency of the Pechini method in the preparation of TiO2samples with nanosize particle. All samples present anatase phase and presence of rutile as secondary phase with content of 15.6, 10.5 and 18.3%. The isothermal adsorption showed that samples have mesopores characteristics and morphology with irregular shape agglomerates. The sample 4:1 presented better photocatalytic performance discoloring 70% of dye in 24h, indicating that the presence of 10.5% of rutile phase jointly with anatase phase improve the photocatalytic activity.
Evaluation of Catalyst Ni0.4Cu0.1Zn0.5Fe2O4 on Methyl Esterification of Free Fatty Acid Present in Cottonseed Oil
Authors: Dantas Joelda , Silva A.S. , Santos P.T.A. , Santos J.R.D. , Barbosa D.C. , Meneghetti Simoni Margareti Plentz , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

This study aimed to assess the performance of the solid catalyst Ni0.4Cu0.1Zn0.5Fe2O4, synthesized by combustion reaction, over the methyl esterification reaction of the fatty acids present in cottonseed oil. The catalyst was characterized by XRD, FTIR pyridine absorption, Raman spectroscopy, and SEM. The reactions were conducted at 140 and 180°C with molar ratios of 1:3, 1:6 and 1:9, with 2% of catalyst and reaction time of 2 h. The XRD results showed that the single phase ferrite was obtained with surface area of 87 m2/g and with mesoporous characteristic. It was observed from the FTIR pyridine absorption only the presence of Lewis acid sites. The Raman spectra confirm the presence of the inverse spinel phase. The results indicated that at 180°C and molar ratio of 1:9, the conversion of free fatty acids was about 87%.
Study of Polymorphs of Zirconia in the System ZrO2: ƞ wt% Re2O3 Obtained by Polymeric Precursor Method
Authors: Muñoz R.A. , Rodriguez J.E. , Silva Cosme Roberto Moreira
Published: August 2012

In this paper we propose the stabilization of zirconium oxide with controlled additions of a rare earth elements concentrate, in the system ZrO2: ƞ wt% Re2O3 (withƞ=5.36, 10.47, 13.74, 16.91 e 20) whereRe2O3is a rare earth elements concentrate composed mainly of 76.88% of yttrium oxide, 12.1% of Dysprosium oxide, 4.04% of Erbium oxide and 1.94% of Holmium oxide. The synthesis method used was the Pechini method. The results show that additions of 5.36 and 20 wt% of the concentrate are enough to stabilize the tetragonal and cubic zirconia phases respectively, and that zirconium oxide polymorphs can coexist with additions within these limit. In the characterization of the obtained powders are presented and discussed the following results: differential scanning calorimetry, transmission electron microscopy and X-ray diffraction. Also, it was necessary to make analysis by Rietveld refinement because they had severe overlap in the diffraction peaks. One of the most relevant results is obtaining a raw material, cheap to be used in many technological applications.
Carbon Nanostructures Synthesize from Coconut Coir Dust Mediated by Layered Clays through Hydrothermal Process
Authors: Barin Gabriela Borin , Bispo Thalita Santos , Giminenez Iara de Fátima , Barreto Ledjane Silva
Published: August 2012

Brazil has a large potential for energy generation and development of new materials from renewable resources through eco-friendly routes, which presents an alternative for construction of an eco-technological platform, where the entire lifecycle of the material or industrial product be sustainable. The proposal of the present work was synthesize carbon nanostructures from coconut coir dust and via template synthesis mediated by layered clays through hydrothermal process. The obtained materials were characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope (SEM). Carbon phase formation was indicated by infrared results with bands at 1444 cm-1and 1512 cm-1assigned to C=C of aromatic groups. Raman spectroscopy results showed presence of carbonaceous species by the appearance of D and G bands assigned to disordered and graphitic crystallites, respectively. SEM results showed overlapping sheets and plates formation. High Resolution Transmission Electron Microscopy measures are in progress.
Nickel Electrodeposition over Powder Compact for Irradiation Target
Authors: Saliba-Silva Adonis M. , Garcia R.H.L. , Martins I.C. , Urano de Carvalho E.F. , Durazzo M.
Published: August 2012

rradiation targets with 20% of 235U (Low Enriched Uranium - LEU) have been studied to replace HEU (Highly Enriched Uranium) targets in future nuclear reactors. These are used to produce the pair of radionuclides 99Mo / 99mTc, used for diagnostics in nuclear medicine. This work aims to develop an alternative route to produce LEU targets. It consists in hydrogenating and powdering metallic uranium and compacting the produced powder, followed by sealing it with nickel by electrodeposition. The deposited nickel should suppress the release of fission gases, and avoid a reactive contact of uranium with aluminum from the enclosure. In order to obtain the best conditions for deposition over uranium, in this work iron powder was compacted into small discs, with a diameter of 22mm and weight of 14g, simulating an equivalent volume of 10g of LEU uranium powder. As well, aluminum discs were used to ensure adhesion and uniformity of the nickel layer. Pulsed nickel electrodeposition was carried out over the compacts, employing current frequency of 900Hz, -0.84A/cm2 of peak current and duty cycle of 0.5 in Watts Bath. The electrical resistance of pulse Ni-plated layer was checked by experiments with impedance spectroscopy in plated samples using aluminum substrate, held in KCl (pH=6), giving EIS results after resting the discs in solution for 0h, 4h and 24h. The physical strength was evaluated qualitatively by treating the Ni covered compact at 600°C, developing a bump deformation on the original planar layer, up to the point to open the Ni-layer for gas relief. These results suggest an adequate mechanical strength of the Ni-layer for using under neutronic irradiation, sealing the radioactive gases, mainly 140Xe, produced during fission of 235U.
Classification and Use of Fine Wastes from Dimension Stone Industry
Authors: Neves Mirna Aparecida , Taguchi Simone Pereira , de Souza Patricia Barcelos
Published: August 2012

Brazil is one of the main producers of dimension stones in the world and most of its production is for international market. Cutting granites and marble blocks to produce plates, and polishing theses plates, generate a fine waste whose characteristics indicate possibilities to be used in other products, such as ceramic material. The residue, also known as abrasive slurry, can cause environmental damage depending on chemical composition. The proper treatment, storage and application of this material ask for studies about their composition and transformations along time. The aim of this work is to analyze five deposits of dimension stone wastes with different ages and stored under different conditions. Residues have high compositional variability, but none showed elements content that could be considered dangerous to the environment.
Purification and Characterization of a Natural Brazilian Clay Blend
Authors: Silva-Valenzuela M.G. , Carvalho Flavio M.S. , Sayeg Isaac Jamil , Sant’Anna L.G. , Valenzuela-Díaz F.R.
Published: August 2012

Clay blends are products used in several industrial sectors, such as petrochemical or pharmaceutical. In this work we describe a natural clay blend occurring in northeastern Brazil. The aim was to purify and investigate their rheological and physical-chemical properties. Foster essays with water and organic solvents were utilized to access the swelling properties of the analyzed sample. Powder X-ray diffractograms (PXRD) were utilized to analyze qualitatively the clay minerals presents in the sample blend. Scanning eletronic microscopy (SEM) and Malvern techniques were used to investigate the sample clay morphology. The purification proceeding allowed separate distinct clay phases with different colors. PXRD analysis demonstrated that each clay phase presents similar structure. SEM and Malvern analysis showed distinct morphology and different size distribution for each clay phase. Our results revealed that the analyzed sample clay may be classified as smectite blend with strong potential for use in pharmaceutical and cosmetic products.
Influence of Organophilization Process Variables in Bentonite Clays from Cubati-PB
Authors: da Silva Carla Dantas , de Oliveira Lima Rosa do Carmo , Costa Julliana Marques Rocha , Neves Gelmires Araújo , Ferreira Heber Carlos
Published: August 2012

This work aims at the development of organoclay from two varieties of bentonite for use in organic media using ionic surfactants, studying the influence of process variables in the organophilization process. We used the following materials: natural bentonite clay from Cubati-PB District, and the ionic quaternary ammonium salt: Praepagen WB® with 45% active matter. The clays were benefited and then turned into sodium form and subsequently into organoclays. The bentonites were characterized by laser diffraction (GA) X-ray fluorescence chemical composition (EDX), thermogravimetric analysis (TGA), thermogravimetry (DTA) and X-ray diffraction (XRD). The organoclays were characterized by (XRD) thermogravimetric analysis (TGA) and thermogravimetry (DTA). The results showed that the clay has potential for application in the organophilization process and that there is influence of process variables.
Effect of Addition of Quasicrystals in the Formation of Geopolymer Matrix Composites
Authors: Silva Adiana Nascimento , Altidis Jaqueline Dias , Menezes Romualdo Rodrigues , dos Passos Tibério Andrade , de Barros Silvio Romero , de Lima Severino Jackson Guedes
Published: August 2012

The geopolymer although being a recently discovered material, it is already present in many industrial sectors. This range of applications is due to the commitment of the scientific community to understand and manipulate the material, seeking a contribution in this regard, it has produced geopolymer matrix composites with quasicrystalline and reinforcement, Al62,2Cu25,5Fe12,3 in the proportion of 10%, 20% and 30% by volume. These composites were obtained by manual production and heat treated at 400 º C for two hours. The characterization was made with the aid of scanning electron microscopy (SEM) and x-ray diffraction (XRD). Diffractograms of composites without heat treatment showed characteristic peaks of the phases present in the matrix and reinforcement. For the composites with heat-treated, it was observed that besides the phases mentioned above the presence of diffraction peaks possibly associated phase silica sodium aluminate. The composite showed good interface quasicrystal / geopolymer, showing the existence of a phase with lamellar morphology in the treated material.
Study of the Application of Non-Plastic Clays from Poços De Caldas - MG
Authors: Maestrelli Sylma Carvalho , Roveri C.D. , Mariano N.A. , Faustino L.M. , Aielo G.F. , Pinto L.P.A. , Manochio C. , Nunes A.G.P. , Cal T.M.L. , Ribeiro F.F.
Published: August 2012

The manufacture of ceramic products involves the knowledge of the whole process, starting with the raw materials that are traditionally treated as clays. The term clay according to Santos [1] means a material with earthy texture and low grain size, which develops plasticity when mixed with a limited amount of water. The clay (or mudstone from the geological point of view) is a finely divided rock, consisting mainly of clay minerals, plastic materials and minerals that may contain non-plastic, and some materials which are not considered clay minerals, such as calcite, dolomite, gibbsite, quartz, alumina, pyrite, and others. Chemically, clays are composed of hydrated silicates of aluminum and iron, containing also a certain amount of alkaline and earth alkaline elements.
Mixture of Granite Waste and LD Steel Slag for Use in Cement Production
Authors: da Costa Borges Adriano , Gadioli Monica Castoldi Borlini , Pinto Luiz Alberto Baptista , de Oliveira José Roberto
Published: August 2012

A great amount of granite waste and steel slag is generated daily in Brazil, being those constituted mainly by SiO2and CaO, respectively. The objective of this work was to characterize the material formed after melting and cooling of the mixture of granite waste and LD steel slag, with basicity (CaO/SiO2) of 1.0, aiming to evaluate the technical feasibility of this to the Portland cement production. Two samples were prepared and melted. After the melting of the mixture, one sample was cooled in water and another in the furnace. The samples characterization was carried out through X-ray diffraction and scanning electron microscopy. The results showed that the new material formed presented amorphous state, to the samples cooled in water and akermanite and gehlenite phases, considered ideals for the hydraulic activity of the slags, in the sample cooled in the furnace. Therefore, the mixture of those two wastes can be a new alternative for the use of both, allied to the decrease of the environmental impact.
Tire Rubber Powder/ Rice Husk Ash Polymer Compound
Authors: Wiebeck Hélio , Valenzuela-Díaz Francisco Rolando , Esper Fabio José , Martín-Cortés Guillermo Ruperto , Hennies Wildor Theodoro , Costa Marcus V.V.
Published: August 2012

The advantage of the incorporation of tire rubber powder and rice husk ash in the polymer compound is mainly due to the reduction of the products cost, as well as improving the essential properties for a great processing of the material, for example, its flow into a hole of a thin wall mold. The rice husk ash can replaces the carbon black in the new products, contributing with the improvement of the environment and the economy of the society. Main objectives of this work are: enhance the applications of the ashes from the rice husk and the waste from the tire rubber, as well as, study new methods of recycling of polymeric wastes, to incorporate an aggregated value to the recycled materials as well as obtaining compounds or nanocompounds materials.
SEM, XRF, XRD, Nitrogen Adsorption, Fosters Swelling and Capacity Adsorption Characterization of Cloisite 30 B
Authors: Patrício Aline Cadigena Lima , da Silva Marcílio Máximo , de Sousa Anna Karoline Freires , Mota Mariaugusta Ferreira , Freire Rodrigues Meiry Glaúcia
Published: August 2012

Cationic surfactants, such as quaternary ammonium cations, have been used, in order to ameliorate the oil sorption capacity of inorganics materials, such as clays. Clays modified with quaternary ammonium cations (organoclays) have better performance in sorption, remove oil and grease from water at seven times the rate of activated carbon, as well as they can be used like perforation fluids of oil wells to the oil base, lubricants, among others industries. This work aims characterize the Cloisite 30B using various techniques: X-Ray Diffraction (XRD), Specific Surface Area (BET) and Cation Exchange Capacity. Different organic solvents, namely gasoline, diesel and kerosene were used in order to investigate the clays compatibility after orgophilization.
Effect of Gel Chemistry on the Machinability of Green SiC Parts Produced by Gelcasting
Authors: Riviello André Marques , Ortega Fernando dos Santos
Published: August 2012

The growing interesting in the use of silicon carbide in automotive components, biomaterials, energy, among others, which demand the production of parts with complex geometry that are difficult to obtain by conventional compaction techniques, motivates the search for developing new conformation processes. Within this context, this paper investigates the production of pieces of silicon carbide through the gelcasting process and subsequent green machining of these parts. Three systems of monomers were studied: MAM-NVP-MBAM, MAM-PEG (DMA) and MAM-HMAM. The effect of the concentration of monomers, concentration of chemical initiator and the ratio of chain-forming and crosslinker monomers on the cutting force during machining and surface roughness were evaluated. These data are compared with values of flexural strength and hardness of samples produced under the same conditions. Through a statistical analysis it was determined the best formulation for the production of parts of SiC with favorable characteristics of green machining.
Characterization and Efficiency Evaluation of Regenerated Filter Media
Authors: de Barros Priscila Martins , Tanabe Eduardo Hiromitsu , Aguiar Mônica Lopes
Published: August 2012

This study aimed to evaluate the characteristics of virgin and regenerated filter media and their relation with filtration efficiencies for particles with aerodynamic diameter up to 20 µm. The permeability of the filter media was determined and their fibers were observed in a scanning electron microscope. Filtration efficiency was obtained from the dust cake formed. The particulate matter used was phosphate concentrate and the filter media were cellulose fiber filters. The results showed that regenerated filter media presented higher air permeability due to the opening of the fibers observed in the microphotographs obtained; lower removal efficiencies were observed for particles smaller than 2.5 µm; and for particles larger than 2.5 µm, the efficiencies were nearly the same as those of the virgin filter, which was approximately 100%. It was verified that the regenerated filter media lost their initial characteristics, but continued to be efficient for particles larger than 2.5 µm.
The Samarium Depleted Zone in SmCo5 Magnets
Authors: de Campos Marcos Flavio , Landgraf Fernando J.G.
Published: August 2012

After sintering, SmCo5magnets may present a surface layer depleted in Samarium. This happens because Samarium is much more susceptible for oxidation than cobalt. Besides, samarium has high vapour pressure. This Sm depleted zone is of the order of ~ 1 mm (in a 10 mm diameter magnet), and present oxygen content 1000 ppm higher than the center of the magnet. This layer is composed by SmCo(5+x), which presents low coercivity (1-2 kOe). The occurrence of the Sm depleted layer is associated with kinks in the 2ndquadrant of the hysteresis curve. After the removal of this layer, the hysteresis kinks disappear. The efficacy of different chemical etchings (Nital and chromic acid) to reveal microstructural constituents was discussed in detail. Nital is recommended for observation of magnetic domains under polarized light (Kerr effect), whereas chromic acid is more suitable to identify Sm2Co7and other high Sm phases.
Study of the Processing Conditions Used to Incorporate an Antimicrobial Additive in Thermoplastic Polymer
Authors: Duarte Glaucea Warmeling , Tachinski Camila Gaspodini , Naspolini Angélica Melo , Consenso Eloisa Contessi , Salvan Ramon Fernandes , Cordova Victor Hugo , Piletti Raquel , Riella Humberto Gracher , Fiori Márcio Antônio
Published: August 2012

In the latest years, several studies were realized concerning about the application of biocidal compound in polymers or ceramics, due to the risk offered to human life by the action of pathogenic microorganisms. Many of these materials, considered special, are directed to medical area and to the food industry, for the production of food packaging. Essential oils (EOs) are aromatic liquids obtained from plant material that have bactericidal activities. One example of essential oil is Eugenol, major component of clove oil. Eugenol is the essential oil compound that better reduce the bacterial activities. This work aimed to study the processing conditions used to incorporate an antimicrobial additive in polypropylene in order to find the processing conditions in which the sample obtained have the best bactericidal properties. To evaluate the effect of the processing conditions in the bactericidal action of the compound it was used an statistical experimental factorial planning. The samples obtained underwent microbiological and physical tests to prove its antibactericidal efficiency. The preview results obtained showed significance to some of the studied variables.
Recycling of Electric Arc Furnace Dust by Adding to Hot Metal
Authors: Sobrinho Vicente de Paulo Ferreira Marques , de Oliveira José Roberto , Telles Victor Bridi , Grillo Felipe Fardin , Tenório Jorge Alberto Soares , Espinosa Denise Crocce Romano
Published: August 2012

This research aims to study the process of incorporation of the metal iron contained in electric arc furnace dust (EAFD), by addition in hot metal at a temperature of 1,400 degrees Celsius altering experimental conditions such as how to add the EAFD (“as received” and in the form of briquettes), the percentage of EAFD to be added (10, 20 and 30% of initial weight of sample pig iron). The time of withdrawal of the sample of pig iron and slag (30 minutes after the addition of EAFD). Previously, the EAFD will be characterized using the following techniques: chemical analysis, particle size analysis, X-ray diffraction, scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) microanalysis. After characterization, the electric arc furnace dust to be added to the bath of liquid iron, will be divided into 2 types: the first order of addition will be in the form "as received" from the plant and the second is through the agglomeration of EAFD in the form of briquettes. The achievement of fusion experiments in laboratory scale will take place in a vertical tubular furnace with temperature control. The fusion experiments to assess the incorporation of the metal iron will use graphite crucibles. A flow of inert gas (argon) will be maintained inside the furnace during the experiments. It is expected that the results obtained at the end of the research allow the evaluation of the iron metal incorporation of electric arc furnace dust in pig iron bath.
Study Intercalation and Mechanical Properties of Nanocomposites of HDPE/Organoclay
Authors: Costa da Silva Milena , de Oliveira Sara Verusca , de Mélo Tomás Jefférson Alves , Araújo Edcleide Maria
Published: August 2012

Nanocomposites are hybrid materials that can be obtained with, three, two or bust one-dimensional in nanoscale found in particles dispersed in the matrix. By presenting a nanometric structure, this new class of materials may have only properties, different from traditional composites and their constituents, which may be established in the synthesis process. The aim of this work is prepare nanocomposites of HDPE/ bentonite clay by melt intercalation technique. Systems were evaluated for the presence of untreated clay and chemically treated (organoclay) with two different types of quaternary ammonium salts, Cetremide and Dodigen. In the preparation of nanocomposites were obtained concentrated using a high speed mixer and then the nominal percentage of clay was dispersed in a twin screw extruder corrotacional. The systems were characterized by X-ray diffraction and mechanical properties. The XRD patterns of nanocomposite of HDPE/organoclay suggest a not intercalated structure. The mechanical properties of nanocomposites presented reducing values in relation to pure polymer.
Thermal Aging of Reprocessed NdFeB Powders
Authors: Périgo E.A. , Landgraf Fernando José Gomes
Published: August 2012

Microstructural and magnetic properties of thermal aged NdFeB-based powders, recycled by means of the HDDR process, are studied. The time aging causes a reduction of the remanent magnetic moment per unit mass and intrinsic coercivity of the magnetic powders. On the other hand, it has been verified an increase of the magnetic polarization atµ0H= 2 T after aging during 16 hours. The oxygen concentration is superior in the grain boundary region (Nd-rich) compared to that verified in the hard magnetic phase.
Experimental and CFD Simulation of a Bubble Column
Authors: Ribeiro J.A. , Reis A.S. , Avendaño P.S. , Ataíde C.H. , Barrozo Marcos A.S.
Published: August 2012

The numerical simulation in fluid mechanics has large application in chemical engineering. The objective of the present work is the analyze of a computational model for the fluid dynamics behaviour of a bubble column of the geometry cylindrical non regular with multiphase mixture. Experimental data and CFD results of the hydrodynamics of gaseous and liquid phases have been compared. Five different diameters of bubbles have been used in the CFD simulations. The comparisons between CFD simulations and experimental data show that the Eulerian-Eulerian approach provides a computational model that represents the process satisfactorily.
Study of Measurement Methods of Particle Velocity in a Spouted Bed
Authors: Santos D.A. , Alves G.C. , Barrozo M.A.S. , Duarte Claudio Roberto
Published: August 2012

Average particle velocity measurements were carried out in a conical-cylindrical spouted bed made of acrylic. In this study an intrusive fiber optical technique which is based on a cross-correlation function between signals from its two channels was used. For a non-intrusive measurement in order to compare with the intrusive technique, images of particle movement were recorded using a high-speed video camera. The experiments were conducted in differents air velocity conditions above the minimum spouting velocity. The latter method was limited in velocity measurement only near the spouted beds wall inasmuch as the spouted bed used was a three dimensions one. On the other hand, the fiber optical is a promising technique for measuring particle velocity distributions in a three dimensions spouted bed. To predict the minimum spouting velocity in order to use this result in the measurement techniques investigation, simulations were carried out using the Eulerian-Eulerian multiphase model.
Experimental Study of the Influence of Vortex Finder Geometry on Hydrocyclones Performance
Authors: Silva D.O. , Façanha J.M.F. , Vieira L.G.M. , Barrozo Marcos A.S.
Published: August 2012

The use of hydrocyclones for particles separation is widespread due to advantages such as low cost, simple structure, large capacity and low volume. The shape and size of a hydrocyclone has a decisive effect on the internal flow structure of the continuous phase, and therefore, the separation or classification of the dispersed phase [1]. Therefore, in order to improve the equipments performance, several geometrical changes have been studied in the literature for hydrocyclones of different families [2-13].
Adhesion Tests in Quasicrystal Powders Reinforced Geopolymer Composites
Authors: Altidis Jaqueline Dias , de Barros Silvio Romero , de Souza João Dellonx Régis Barboza , Torres Sandro Marden , de Lima Severino Jackson Guedes
Published: August 2012

The composite studied here consisted of a geopolymer matrix reinforced with quasicrystal powders. Quasicrystals are complex metal alloys with atypical structures. Due to their physical, mechanical and surface properties, quasicrystals have been widely studied. Nowadays quasicrystalline powders are proposed to be incorporated in ductile matrices. The geopolymers are inorganic polymers with excellent thermal performance and interesting adhesive properties. The quasicrystalline alloys were prepared by induction melting the constituents under argon atmosphere in a water-cooled copper crucible. In this work the adhesion of composites with 5, 10 and 15% of quasicrystal powder in aluminum joints was investigated. In addition, the influence of the curing time was taken in to account and tests were performed in samples with 7 and 28 days of cure. The results indicate an improvement in adherence with the inclusion of quasicrystal. The best adherence was obtained when the curing time was 28 days.
Solid - Phase Transformations of Anthracene in High Temperature Treatment
Authors: Almeida Luciana Lezira Pereira , Skury Ana Lúcia Diegues , Guimarães R.S. , Monteiro Sérgio Neves
Published: August 2012

The process of diamond synthesis using metal as a catalyst-solvent is a great method of industrial production by using high pressures and high temperatures. Several aromatic hydrocarbons are already studied for the process of graphitization of carbon, many have already been tried for use as raw materials for diamond synthesis. The graphitization of anthracene was carried out at a pressure of 3Gpa at a temperature of 1000°C. The graphite was produced in mixed Ni-Mn alloy for diamond synthesis process at a pressure of 4.5 GPa at a temperature of 500° to 1300°C. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used to characterize the transformation of graphite into diamond produced with anthracene starting at high pressures and high temperatures. The results of this study show that there is a diamond shape through an aromatic hydrocarbon at high pressures and temperatures with a catalyst-solvent process.
Study of Biological Material Separation in Hydrocyclones
Authors: Bicalho Isabele Cristina , Mognon José Lucas , Shimoyama Juliana , Ataíde Carlos Henrique , Duarte Claudio Roberto
Published: August 2012

Hydrocyclones use the same principle of separation of centrifuges, but with no moving parts and no mechanical complexity. For these reasons as well as its versatility in applications, low cost, simple operation, small size, high production efficiencies with short residence times, these devices have been widely found in industry, and even suggested as a practical alternative to solid-liquid separations involving biological material. In the process of fermentation to produce ethanol, the yeastSaccharomyces cerevisiaeare recovered and recycled to a new stage of fermentation. This separation process is a major challenge, because the yeasts are small and low density. In this sense, the objective of this work was to investigate the use of hydrocyclones for the separation of yeast from alcoholic fermentation. A factorial experimental design (24) was applied and the results were used to determine empirical mathematical model that describes the reduced separation efficiency as a function of different geometrical and operating variables.
Laser Modified Thin Layers in Piston Rings
Authors: de Oliveira Felipe , de Rossi W. , Rossi J.L.
Published: August 2012

The new engine developments are providing engine mechanical and thermal loads increase on the components. Besides the unfavorable wear conditions, the components should provide similar or improved performance compared with current baselines. For piston rings, the performance is given by the ring capacity of sealing and scrapping. These performances can be measured in an engine using the results of lube oil consumption and blow-by. The main intention of this work is to provide support for new piston rings developments by laser hardening parameters optimization, reducing the wear degradation. Hence, the aim of this work was to evaluate the influence of laser hardening on contact surface from the second ring and verify the microstructure modification and rings shape distortion due to heat input. The results indicate that the laser parameters can be tailored in order to achieve adequate macrostructures and micro constituents distribution. The ring ovality was inside to acceptable levels.
Powder Injection Molding of Multimaterial Parts - Self Lubricating Steel Combined with Plain-Carbon Steel
Authors: Schroeder Renan , Filho Antônio I. Ramos , Binder Cristiano , Klein Aloisio N.
Published: August 2012

Powder Injection Molding allows processing of multifunctional parts through combination of different materials in a single structure. This technique so-called Two Components Powder Injection Molding has been developed some years ago and now is rapidly being considered for many engineering applications. In this paper, some important aspects of materials selection and processing conditions are reviewed in order to look insight of the technology. To show how successful can be the technique, carbonyl iron feedstock was co-sintered to the recently developed self-lubricating steel, aiming at different tribological properties in each side of the final component. Defect-free parts were obtained and the tensile resistance was in the same range of single material parts, representing a very strong bonding interface.
Synthesis and Characterization Nanoparticles ZnAl1.94(Yb:Er)0.06O4 Functionalized with Chitosan
Authors: Furtado Cristiane M. , de Araújo Pascally M.A. Guerra , dos Santos Patrícia T.A. , de M. Costa Ana Cristina F.
Published: August 2012

This work aims to synthesize combustion reaction, functionalized with chitosan nanoparticles and characterize ZnAl1.94(Yb:Er)0.06O4, codoped with x = 0.06 mol in the proportion 5:1 of Yb:Er. Nanoparticles before and after functionalization were characterized by XRD, TGA/DTA, FTIR and SEM. The results show that before and after functionalization presented ZnAl2O4majority phase and Al2Yb4O as secondary phase. Multiple bands around 1100 cm-1and 1040 cm-1corresponding to the asymmetric stretching Si-O confirms the functionalization of nanoparticles. Nanoparticles presented before functionalization morphology heterogeneous, consisting of clusters of particles with near-spherical shape, large particle size distribution, consisting of large clusters with size around 3 µm and smaller clusters in the shape of plates with size in order of 0.5 µm. After functionalization, the morphology shows the formation of a film consisting of amorphous phase and crystalline phase. The mass loss for the nanoparticles before and after functionalization was 7.2 and 39%, respectively.
Microstructure and Adhesion of Diamond Composites
Authors: de Oliveira Luciano José , Filgueira Marcello
Published: August 2012

Typically, diamond tools produced by Powder Metallurgy are very effective in cutting processes in general, because are used diamond composites for cutting action. In these tools, diamond abrasive grains are embedded in the metal matrix. Some of the most common examples of these tools are the cutting discs, abrasive crowns, drills and diamond wires. This work studies the Fe-Cu-Co-diamonds composites processed by the powder metallurgy techniques powders mixing and hot pressing at 850°C/35MPa/3 min. Microstructural analysis of composites as well as metal matrix-diamond adhesion was made by scanning electron microscopy-SEM after abrasion resistance tests. Compression tests were carried out to evaluate the elastic properties of composites, i.e., modulus of elasticity (E) and yield stress (σe), aiming at the assessment of the metal matrix-diamond adhesion. It was found satisfactory adhesion for the composites M2 and M3, with values σe = 360 MPa and 375 MPa, respectively. Keywords: diamond tools, powder metallurgy, composite Fe-Cu-Co-diamond.
Physicochemical Analysis of Ti-Si-B Powder Alloys
Authors: de Oliveira Guilherme , de Fátima Magalhães Mariano Samantha , Fernandes Bruno Bacci , Ueda Mario , Ramos Alfeu Saraiva
Published: August 2012

Titanium alloys of Ti-Si-B system were manufactured by blended elemental powder method using Ti, Si and B powders as starting materials. It was found that uniaxial and isostatic pressing followed by hot pressing at around 1000°C, for 20 minutes, provided good densification of such alloys. The physicochemical studies were performed by means of scanning electron microscopy, X-ray diffraction, atomic force microscopy and microindentation/wear tests. The investigations revealed a multiphase microstructure formed mainly by α-titanium, Ti6Si2B, Ti5Si3, TiB and Ti3Si phases. The phase transformations after pressureless sintering at 1200°C was also studied by X-ray diffraction for the Ti-18Si-6B composition. As stated in some other researches, these intermetallics in the α-titanium matrix provide high wear resistance and hardness, with the best wear rate of 0.2 mm3/N.m and the highest hardness of around 1300 HV.
Mechanical Properties of Composite AA2024 Matrix with Aluminium Carbide Dispersed by High Energy Milling
Authors: Breitenbach E.R. , Costa C.E. , Folgueras M.V. , Milan J.C.G. , Antonelli R.J. , Silva F.C.
Published: August 2012

Dispersion strengthened aluminium composites have been prepared by mechanical alloying. At this work were studied the turning conditions to getin situformation and dispersion of Al4C3on 2024 alloy by graphite addition. The alloy matrix was obtained by attrition milling a mixture of starting powders; further additions of carbon (2,5; 5 and 10% wt) were performed by means of a planetary mill. Through an adequate sintering the reinforcement formation was showed by X-Ray diffraction analysis of powders with milling times next to 20 hours. The microhardness values appointed that mechanical properties were held even soft material addition (graphite) and improved by age hardening. Pin-on-disc test revealed the composite have low friction coefficient, due to lubricant carbon action and enough low volumetric wear due to high hardness of bulk Al4C3reinforcement.
Nanoparticles Consolidation Mechanism at High Pressure and High Temperature in Diamond-B-Si-Cu System
Authors: Skury Ana Lúcia Diegues , Monteiro Sérgio Neves , de Azevedo Marcia G. , dos Santos Angelica da Cunha , Bobrovnitchii Guerold S.
Published: August 2012

The synthesis of advanced materials with superior performance and properties is of growing scientific and technological interest. In particular, significant achievements have been attained in the synthesis of nanocomposites associated with superhard materials. This work investigates nanostructured composites obtained by high pressure and high temperature sintering of synthetic diamond combined with boron, silicon and copper. Diamond powder was mixed with B, Si and Cu, also in the form of powder. The mixture was then submitted to high energy wet milling until a nanopowder was formed. Sintering of this resulting nanopowder was carried out at 5.6 GPa of pressure and 1300°C. X-ray diffraction and scanning electron microscopy analysis revealed the formation of new phases in a well consolidated nanostructure with relatively high density.
Application of Sintered Steel for Synchronizer Rings Used in Mechanical Transmissions
Authors: Andrade T.F. , Zambon A.C. , Sena C.H.C. , Bida A.G. , Kavai J.R.
Published: August 2012

Synchronizer rings are mechanical components that equalize the gear rotation to be engaged with the sliding sleeve. It is done by the friction property of the synchronizer ring material. Different types of materials are used to manufacture synchronizer rings depending on the application. There are basically two groups of material: dual function, structural and friction properties (Cu-Zn alloys, Al-Si alloys, etc.) and single function, only structural property (rolled and sintered steels, Cu-Zn alloys, Al alloys, etc.). The objective of this work was to propose a solution to the synchronizer ring structural material of a new mechanical transmission design. This component was initially designed with a Cu-Zn alloy and showed premature failure on synchronizer teeth during tests. To eliminate this problem several technical alternatives were analyzed considering the best cost and benefits ratio, defining to use the sintered steel FLC-4908 per MPIF Standard 35.