bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Civil Construction Waste and its Incorporation to Mortar
Authors: Cunha G.A. , Andrade Antonio C.D. , Souza Joao Monerrat M. , Evangelista Ana Catarina J. , Almeida Valeria C.
Published: October 2010

As the preservation of the environment is a big concern nowadays, plenty of studies have arisen in order to decrease the production or reuse the waste from human activities. In this context, the civil construction industry comes up, as it is able to incorporate waste to mortar, being a great alternative for the reuse of solid waste. The scope of this work has been the characterization of Construction and Demolishment Waste (RCD) and its incorporation to the mortar aiming at the development of alternative construction materials in the future for the economical reutilization of waste discharged in embankments and landfills so far preserving the environment so far. The experimental studies taken with sample bodies, such as water absorption, resistance to compression, X-ray diffraction, X-ray fluorescence and scanning electronic microscopy, elicits the viability of the partial substitution of cement by RCD mixed waste, taking its different applications into consideration.
Characterization of Sugarcane Bagasse Ash for Use in Ceramic Bodies
Authors: Faria Katia C.P. , Gurgel R.F. , Holanda J.N.F.
Published: October 2010

The objective of this work is to characterization of sugarcane bagasse ash waste aiming the use it in red ceramic industry. The characterization was done in terms of chemical composition, X-ray diffraction, particle size distribution, morphology, and plasticity. The results show that the cane bagasse ash waste is a non plastic material, which contains high content of silica and minor amounts of Al, Fe, Ca, Mg, and K oxides. Thus, the sugar cane bagasse ash waste presents high potential for application in the manufacture of ceramic products such as bricks, roofing tiles, and ceramic tiles.
Chemical-Environmental Characterization of Waste Coming from Petroleum Industry for Application in Clay Ceramics
Authors: Pinheiro Bruno C.A. , Holanda J.N.F.
Published: October 2010

The petroleum industry generates huge amounts of oily sludge during the process of oil and gas extraction. This waste is a pollutant material that can cause environmental damage. Because of this, it has been treated with bentonite clay, being referred as encapsulated petroleum waste. In this work the chemical-environmental characterization and classification of the petroleum waste were done according to ABNT standards. The results indicated that the encapsulated petroleum waste should be classified as Class IIA – “No Inert”. Therefore, it could be used in manufacture of ceramic products for civil construction.
Synthesis of Zeolite Membrane (Y/α-Alumina)
Authors: Araújo Ana Paula , da Silva Valmir José , Crispim Alana Carolyne , Menezes Romualdo Rodrigues , Freire Rodrigues Meiry Glaúcia
Published: October 2010

The general aim of this study was to develop materials of the type: Y zeolite (hydrothermal synthesis), ceramic support (forming of powder) and zeolite membrane (rubbing). The preparation of the Y zeolite was conducted in accordance with the hydrothermal synthesis method, the time of crystallization was one day. The ceramic support was prepared by means of the forming of powder technique and subsequently subjected to sintering at a temperature of 1400°C/1h. The zeolite membrane (Y/α-alumina) was prepared by secondary growth method (rubbing). These materials were characterized by XRD and SEM. Obtaining Y zeolite could be confirmed by X ray diffractograms. From the images obtained by SEM, it was possible to derive from analysis that the Y zeolite is composed of a homogeneous morphology, where the particles are crowded, with uniform size. The results obtained for the ceramic support (α-alumina) showed that it displays characteristics peaks of aluminum oxide. By using micrographs it was possible to observe a heterogeneous microstructure with a compact form, without cracks upon the layers. According to the XRD, for the methodof secondary growth (rubbing), it was observed that the Y zeolite wich had been synthesized on the ceramic support displayed a crystalline structure. The micrography of the zeolite membrane (Y/α-alumina) showed the formation of a layer of zeolite on the ceramic support.
Cutting Performance of Diamond Coated Si3N4 Tool During Turning
Authors: Souza José Vitor C. , Nono Maria do Carmo de Andrade , Machado João Paulo Barros , Silva Olivério Moreira Macedo , Melo F.C.L. , Ribeiro M.V.
Published: October 2010

Silicon nitride cutting tools have been used successfully for machining hard materials, like: cast irons, nickel based alloys, etc. However these cutting tools with diamond coating present little information on dry turning operations of gray cast iron. In the present work, Si3N4 square inserts was developed, characterized and subsequently coated with diamond for dry machining operations on gray cast iron. All experiments were conducted with replica. It was used a 1500, 3000, 4500 m cutting length, feed rate of 0.33 mm/rev and keeping the depth of cut constant and equal to 1 mm. The results show that wear in the tool tips of the Si3N4 inserts, in all cutting conditions, was caused by both mechanical and chemical processes. To understand the tool wear mechanisms, a morphological analysis of the inserts, after experiments, has been performed by SEM and optical microscopy. Diamond coated PVD inserts showed to be capable to reach large cutting lengths when machining gray cast iron.
Influence of Alkaline Activation over Swelling and Cation Exchange Capacity on Bentonites
Authors: Rosário Jeane A. , Silva Laura A. , Moura Gabriel Beraldi G. , Gusatti Marivone , Lima Raquel B. , Brys Miguel E.P. , Kuhnen Nivaldo C. , Riella Humberto Gracher
Published: October 2010

The performance of the alkaline processes on the properties of cation exchange capacity (CEC) and swelling was studied in three different types of bentonite from Brazil, Argentina and Mozambique. Alkaline activations were performed by means of mechanochemical reactions with solutions of NaOH and Na2CO3, to increase the sodium content of bentonite clays and, thus, improve the properties above. Clay samples were characterized by X-ray diffraction, to obtain the constituent phases. Activated samples were evaluated according to their cation exchange capacity – determined by the methylene blue test, and swelling index – measured by the Foster’s method. Results showed that the activation improved the properties of all bentonite types, especially the Brazilian clay, which achieved the most significant raises. There was also an indication that the type of clay affect the processing.
Analysis of Used Vegetable Oils Treated with Paraíba/Brazil Clays by Kinematic Viscosity
Authors: Araújo Elaine Patrícia , Araújo Edcleide Maria , Fook Marcus Vinícius Lia , de Oliveira Sara Verusca , Silva Divânia Ferreira , Medeiros Keila Machado
Published: October 2010

The search for new sources of renewable energy order to minimize environmental impacts has led the scientists to develop new alternatives, such as the use of recycling of frying oils to produce biodiesel. The utilization of fuels of agricultural origin in the cycle diesel engines is a good alternative to reduce dependence on importation petroleum, since these fuels are a renewable source of energy. The utilization of biodiesel as biofuel is a contribution to the environment, reducing the qualitative and quantitative form levels of environmental pollution. However, these oils should go through a process of decontamination and decoloration up the stage of chemical conversion which is used clay to lighten the oil. This study aimed to characterize clay of Paraíba to be used in the clearing of frying oil. It was observed through the technique of kinematic viscosity the clays show good results in treatment used vegetable oils.
A Study of the Behavior of Phosphatic Concentrate in Gas Filtration Cake Formation
Authors: Fargnoli Amélia Giovana , Matugi Karina , Martinatti Isabela , Aguiar Mônica Lopes
Published: October 2010

The purpose of this study was to investigate the porosity behavior of dust cakes formed by phosphatic concentrate along filtration time. Filtration trials were performed for four different pressure drops. The fabric filter used as filter medium was a polyester felt. The dust cakes obtained were submitted to a hardening process and their images were acquired with the use of a SEM. The images generated by the SEM were analyzed by using an image analyzing program that supplied the cake porosity values. Porosity values were also estimated using Ergun’s modified equation. Results show that porosity presents higher values when calculated using the image analyzing program, but has the same behavior as the results found with Ergun’s equation. It was also observed that porosity is not constant during filtration; therefore it can be concluded that the dust cake is compressible.
Polysulfone Activated Carbon Composite Membranes
Authors: Anadão Priscila , Sato Laís Fumie , Wiebeck Hélio , Valenzuela-Díaz Francisco Rolando
Published: October 2010

The addition of a fourth component in the system composed by polymer/ solvent/ non-solvent is a technique generally employed to enhance membrane properties. Since polysulfone presents low hydrophilicity, which can hamper filtration performance, the addition of a hydrophilic material can be an important technique to improve this property. Therefore, the main purpose of this work is to understand the influence of addition of the activated carbon in the system polysulfone/ NMP/ water in terms of membrane morphology, hydrophilicity, thermal and mechanical resistance. From scanning electron micrographs, it could be seen that membrane surface became denser with the addition of higher activated carbon contents and the cross-section morphology was not changed. Acid-base interactions were favored with the activated carbon addition and the availability of Lifshtiz-van Der Waals interactions was decreased, being these two properties very important to avoid fouling formation onto membrane surface. The glass transition temperatures of the polysulfone composite membranes with higher activated carbon contents were increased. However, all activated carbon contents brittled the composite membranes in relation to the pristine polysulfone membrane.
Study of Oxide Layers in Creep of Ti Alloy
Authors: Reis Danieli A.P. , Machado João Paulo Barros , Martins G.V. , de Moura Neto Carlos , Barboza M.J.R. , Couto Antônio Augusto
Published: October 2010

The present study is about the effect of oxide layers in creep of Ti-6Al-4V alloy, in different atmospheres (air, nitrogen and argon). Ti-6Al-4V alloy was treated during 24 hours in a thermal treatment furnace at 600°C in different atmospheres (argon, nitrogen and air). The samples were analyzed by High Resolution X-Ray Diffraction, Scanning Electronic Microscopy (SEM), Atomic Force Microscopy (AFM) and microhardness test. The polished samples of Ti-6Al-4V allloy were treated during 24 hours at 600°C and the oxidation behavior in each case using argon, nitrogen and air atmospheres was observed. The oxidation was more aggressive in air atmosphere, forming TiO2 film in the surface. The oxidation produced a weight gain through the oxide layer growth and hardening by oxygen dissolution. Ti-6Al-4V alloy specimens also were produced in order to test them in creep, at 250 MPa and 600°C, with argon, nitrogen and air atmospheres. When the Ti-6Al-4V alloy was tested under argon and nitrogen atmospheres oxidation effects are smaller and the behavior of the creep curves shows that the creep life time was better in atmospheres not so oxidant. It is observed a decreasing of steady state creep in function of the oxidation process reduction. It is shown that, for the Ti-6Al-4V alloy, their useful life is strongly affected by the atmosphere that is submitted, on account of the oxidation suffered by the material.
Synthesis and Characterization of Organophilic Clay from Cuban Chiqui Gomez Bentonite
Authors: Cortés Guillermo R. Martín , Valera Ticiane S. , Esper Fabio José , Hennies Wildor Theodoro , Valenzuela-Díaz Francisco Rolando
Published: October 2010

Smectites are clay mineral with a layered structure and nanometric thickness, high specific area and a huge variety of uses. Consisting on stacked layers of about 1nm thickness, including two silica tetrahedral and one octahedral sheet. Properties of natural Smectites can be enhanced by organic modification, due to the substitution of the exchangeable cations in the interlayer area. In fact, the properties of the modified smectite (organophilic clay) are related to its modified chemical composition and structural parameters. The interaction of smectite clays with surfactants has an important interest in the fields of drilling fluids, paints, cosmetic, ceramic industries and others. Recent applications are: remediation of contaminated areas and polymer/clay nanocomposites. The aim of this paper is to obtain organophilic clays using a bentonite from the Chiqui Gómez deposit in Central Cuba. The raw and organophilic clays were analyzed by DRX, SEM, swelling capacity in organic solvents and others.
Investigations Hydrodynamics of the Bed Vibrofluidized Rectangular
Authors: Abreu J.M. , Ataíde Carlos Henrique , Barrozo Marcos A.S.
Published: October 2010

In this work the hydrodynamics behaviour of a horizontal vibrofluidized bed (VFB) is analyzed through pressure drop versus air velocity and standard deviations of pressure drop versus air velocity curves with different vibration conditions. The influence of parameters such as frequency and vibration amplitude, as well as bed material loaded, were evaluated and quantified through statistical analysis. A strong linear mass influence was observed on the bed pressure drop for all amplitude levels. For the amplitude it was observed a quadratic function related to pressure. The lowest level of vibration frequency there were the higher velocity values, and they were more accentuated for the intermediate amplitude levels. We found higher values for the minimum vibrofluidization velocity for the same condition of higher mass and intermediate values of amplitude.
Titanium Nitride Deposition in Titanium Implant Alloys Produced by Powder Metallurgy
Authors: Henriques Vinicius André Rodrigues , Lemos T.G. , Cairo Carlos Alberto Alves , Faria Julia , Galvani Eduardo T.
Published: October 2010

Titanium nitride (TiN) is an extremely hard material, often used as a coating on titanium alloy, steel, carbide, and aluminum components to improve wear resistance. Electron Beam Physical Vapor Deposition (EB-PVD) is a form of deposition in which a target anode is bombarded with an electron beam given off by a charged tungsten filament under high vacuum, producing a thin film in a substrate. In this work are presented results of TiN deposition in targets and substrates of Ti (C.P.) and Ti-13Nb-13Zr obtained by powder metallurgy. Samples were produced by mixing of hydrided metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900°C up to 1400 °C, in vacuum. The deposition was carried out under nitrogen atmosphere. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. It was shown that the samples were sintered to high densities and presented homogeneous microstructure, with ideal characteristics for an adequate deposition and adherence. The film layer presented a continuous structure with 15m.
Physical Characterization and Biomass Fluidization (Fume Powder)
Authors: Ataíde Carlos Henrique , Cardoso Cássia Regina , Borges Lais Reis
Published: October 2010

The development of big cities and industrialization has been causing environmental degradation problems, damaging natural and energetic resources, besides the bigger production of wastes. So, it is essential the use of renewable alternative fuels, and industrial wastes processing. Biomass can be used in direct combustion, thermo chemical and biological processes. The fume powder is an important waste of tobacco industries. This work makes a characterization of fume powder, originated from Souza Cruz (Uberlândia unit); the objective is to realize the fast pyrolysis in a bubble fluidized bed. Physical analyses of the powder were made to determine the size distribution, and the medium diameter; the solids density and moisture content (dry base). The elementary composition of the material was also determined. The powder fluidization in an acrylic bed (160 cm heights, 10 cm id), was realized to obtain the minimum fluidization velocity.
Strontium-Doped Neodymium Manganite Powder Obtained by the Solids Mixture Technique
Authors: Vargas Reinaldo Azevedo , Chiba Rubens , Andreoli Marco , Seo Emília Satoshi Miyamaru
Published: October 2010

Many ceramic materials are being studied for application as cathodes in Solid Oxide Fuel Cells (SOFCs), especially aiming to reduce the operating temperature. Several ceramic materials can act as cathodic components, including Strontium-Doped Neodymium Manganite (Nd1-XSrXMnO3). This work contributes to the aforementioned studies by analyzing the main physical, chemical and microstructural characteristics of Nd1-XSrXMnO3 powders, where x = 0.10, 0.30, and 0.50. These powders were obtained by the method of ceramic solids mixture. The homogeneity of the powder particles was found to be suitable for the preparation of suspensions, which can be evaluated rheologically and subsequently molded to the surface of the solid electrolyte.
Filtration of Electrified Solid Particles in a Fibrous Filter
Authors: Rodrigues Marcos V. , Barrozo Marcos A.S. , Coury José Renato
Published: October 2010

The aim of the present work is to verify experimentally the influence of the charge level on collection efficiency during the first stages of filtration. A charge classifier was used to measure the charge level of the aerosol as a function of particle diameter. The filter was made of polypropylene with diameter of 0.047 m and a thickness of 2.6 mm. The solid particles used as test dust were a phosphate rock powder (density 2940 kg/m3 and average Stokes diameter of 3.40 m). The aerosol was dispersed by a TSI Venturi type generator. The particle charging was achieved by a corona charger. In all the tests performed, a linear relation between the particles acquired charge and their diameter was observed. A gradual increase of the charge level was observed with an increase of the tension in the corona charger (0, -3, -6 kV). The filtration results indicated that the global collection efficiency of the filter was very sensitive to the variation of the charge level of the particles. Both efficiency and pressure drop increased when the charge level increased. During the tests, the small increase in pressure drop indicated that the cake had not yet been formed.
Ti-13Nb-13Zr Production for Implant Applications
Authors: Henriques Vinicius André Rodrigues , Silva Cosme Roberto Moreira , Cairo Carlos Alberto Alves , Galvani Eduardo T.
Published: October 2010

Powder metallurgy (P/M) of titanium alloys may lead to the obtainment of components having weak-to-absent textures, uniform grain structure and higher homogeneity compared with conventional wrought products. The production of the Ti-13Nb-13Zr alloy by P/M starting from blended elemental (BE) powders is a cost-effective route considering its versatility and also for allowing the manufacture of complex parts. This alloy due its high biocompatibility and lower modulus of elasticity is a promising candidate for implants fabrication. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering in order to identify the microstructural evolution. Sintered samples were characterized for phase composition, microstructure, microhardness and density. The surface topography of the samples was studied by means of atomic force microscopy (AFM). It was shown that the route is adequate to reach high densities with homogeneous microstructure. Representative AFM images allowed distinguishing a lamellar structure caused by the different phases that are present in the surface of the specimens.
Technology Characterization of Organo-Clays Obtained from Bentonites of the State of Paraiba
Authors: Cortés Guillermo R. Martín , Silva Adriana A. , Pereira Kleberson R. O. , Esper Fabio José , Santana Lisiane N.L. , Hennies Wildor Theodoro , Valenzuela-Díaz Francisco Rolando
Published: October 2010

The organo-clays have important industrial uses between others are: rheological additives for drilling fluids in oil bases, inks, glues, lubricants and cosmetics. At the moment and in a growing way, these materials are considered as important reinforcement fillers in the structuring of nano-composites clays/polymers. They are obtained by the smectite clay reaction with quaternary ammonium salts. In this work an organophillic clay sample prepared by a dry process at the PMT – EPUSP – Metallurgic and Materials Engineering Department of the Polytechnic School at the University of São Paulo, had been characterized basically by techniques of XRD, IR, Thermal Analysis, and by swell capacity of the clays in some oils and organic solvents.
Evaluation of S/S Process of Tannery Waste in Cement by Structural and Mechanical Analysis
Authors: Pinto Carolina A. , Dweck Jo , Sansalone John J. , Cartledge Frank K. , Hamassaki L.T. , Valenzuela-Díaz Francisco Rolando , Albanez N.E.K. , Büchler Pedro M.
Published: October 2010

This paper presents a study of a stabilization/solidification (S/S) process of a tannery waste containing chromium. In this process a mixture of cement, water and the waste is solidified during hydration of the former. Stabilization occurs by the reaction of the chromium components of the waste with the calcium hydroxide formed during the process. A rigid block is obtained with low hazardous of contamination of soil and groundwater after its disposal into industrial landfill. Mixtures were prepared adding dried tannery waste in 10, 15 and 20% of the Portland cement mass. Sodium bentonite and organoclays in 5 % of cement mass were used as additives. Solidified specimens were analyzed after 28 days of hydration time by solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy and unconfined compressive strength analysis. The increase of tannery waste content and the presence of the additives reduce silica polymerization as well as the mechanical strength of the solidified bodies.
Applications of Ultra High-Pressure Powder-Abrasive Waterjet
Authors: Hennies Wildor Theodoro , Cortés Guillermo R. Martín , Lauand V.H. , Lauand Carlos Tadeu , Stellin A. , de Tomi G. , Valenzuela-Díaz Francisco Rolando
Published: October 2010

The paper describes the technique developed for applying garnet powder abrasive ultra-high pressure water jet advanced technology (AWJ) to build accurate models of artistic objects. The objects to be modeled have been selected through a cooperative initiative between the University of Sao Paulo and entities of the private sector. The first application was the reproduction of the artistic floor of marble at the St. Mark's Basilica, Venice, Italy. The other application was the production of official trophies for a technical awards ceremony for a national symposium that took place in Brazil. The trophies were made in stainless steel, whilst the floor reproduction was made in ceramic tiles. The floor was reproduced from high-definition photography of the original floor. The design concept and the blueprints of the trophies were originally conceived by the symposium organizers. Both models have been built using OMAX® CAD/CAM Software, which controls an AWJ unit installed at the University of São Paulo, where the procedures for building both models have been developed and executed with high success.
Determining the Lanthanum Chromite Zeta Potential in Aqueous Media
Authors: Setz Luiz Fernando Grespan , de Mello-Castanho Sonia Regina Homem
Published: October 2010

Lanthanum Chromite may used as interconnect for SOFC’s applications due its particular intrinsic properties as stability in both oxidant and reducing environments and electrical conductivity. However to manufacture these devices that generally present complex shapes as grooved plates and fine pipes, they are necessary the use of the conformation techniques such as screen printing, slip casting, tape casting, extrusion moulding, etc. that are related with colloid processing. Independent of the processing techniques chosen the control of the suspension conditions is important to obtain reproducibility and homogeneous products as final result. In this sense, all contribution to understand the behaviour of the LaCrO3 fine particles in liquid suspension as the surface state using the Zeta’s Potential concepts may supplies information by the forecast of the behaviour during the shaped processing. The aqueous suspensions behaviour was studied utilizing doped lanthanum chromite powders, attained by combustion synthesis. The eletrophoretic mobility measurements of particles in suspension, prepared with the different conditioned powders were made. The electrolyte compositions as function of the pH varying from 2 to 12 were tested. The Zeta potentials and the stability conditions for stable suspensions prepared were determined. The viscosity curves are also appraised.
Isochronal Sintering of Ti-35Nb-7Zr-5Ta
Authors: Henriques Vinicius André Rodrigues , Taddei Elisa B. , Silva Cosme Roberto Moreira
Published: October 2010

Ti-35Nb-7Zr-5Ta alloy is considered an attractive material for implants manufacture due to an excellent combination of properties, including high mechanical and corrosion resistance, beyond the lowest elastic modulus among the titanium alloys. The alloy processing by powder metallurgy (P/M) eases the obtainment of parts with near-net shape forming and low production costs. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 800-1600 °C, in vacuum. The isochronal sintering demonstrated to be efficient for the study of the microstructural evolution. The samples presented high densification and adequate microstructure. The results show that a beta-homogeneous microstructure is obtained in the whole sample extension when sintered at high temperatures beyond that P/M technology allows an effective porosity control.
Influence of the Particle Size on Phase Transformation Temperatures of Ni-49at.%Ti Shape Memory Alloy Powders
Authors: Anselmo George Carlos S. , de Castro Walman Benício , de Araújo Carlos José
Published: October 2010

It is important to control the martensitic transformation start temperature (Ms) of Ti–Ni alloys because it determines the temperature range over which the shape memory effect and superelasticity appear. Powder metallurgy (PM) is known to provide the possibility of material-saving and automated fabrication of at least semi-finished products as well as net-shape components for NiTi alloys. In this study powder with different particle sizes was subjected by gas atomization. The evolution of the control the martensitic transformation start temperature (Ms) was studied by differential scanning calorimetry. The effect of the particle size of powders on the transformation temperatures behaviors was discussed.
Hydrogenation and Discharge Capacity of a La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8 Alloy for Nickel-Metal Hydride Batteries
Authors: Casini Julio César Serafim , Zarpelon Lia Maria Carlotti , Ferreira Eliner Affonso , Takiishi Hidetoshi , de Faria Jr. Rubens Nunes
Published: October 2010

The preparation of negative electrodes for nickel-metal hydride (Ni-MH) batteries using a La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8 alloy in the as-cast state has been carried out. The alloy was mechanically crushed (<44 m) and a battery was manufactured with this material. The mean discharge capacity achieved using this method was 384 mAh/g. Another two batteries were prepared using a hydrogen powdered La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8 alloy at low and high pressures (2-10 bar). It has been shown that hydrogen powdering facilitates the activation of the negative electrode for Ni-MH batteries. This study also included the characterization of the hydrogenated and crushed powders. These materials were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD).
The Effect of High Charging Rates Activation on the Specific Discharge Capacity and Efficiency of a Negative Electrode Based on a LaMgAlMnCoNi Alloy
Authors: Ferreira Eliner Affonso , Zarpelon Lia Maria Carlotti , Casini Julio César Serafim , Takiishi Hidetoshi , de Faria Jr. Rubens Nunes
Published: October 2010

A nickel-metal hydride (Ni-MH) rechargeable battery has been prepared using a La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8 alloy as the negative electrode. The maximum discharge capacity of the La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8 alloy has been determined (350 mAh/g). Using a high starting charging rate (2857 mAg-1) an efficiency of 49% has been achieved in the 4th cycle. The alloy and powders have been characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD).
Determination of the Crystal Alignment of Pr-Fe-B Magnets Using the (105) X-Ray Pole Figure
Authors: Castro A.R.M. , Takiishi Hidetoshi , de Faria Jr. Rubens Nunes , de Lima Nelson Batista
Published: October 2010

The crystallographic alignment of various permanent magnets has been investigated by X-ray pole figure analysis. Attempts have been made to measure the degree of alignment of these sintered magnets using the (105) reflection. It has been shown that the (105) pole figure can be used only to verify small differences in texture in magnets high degree of crystallographic alignment. A comparison between the measured and the calculated L105 index showed good agreement.
Microstructural Analysis of Hardmetal Using WC Nanometric Powders
Authors: Oliveira H.C.P. , Borges L.H.F. , Tardim Rômulo Crespo , Freitas M.S. , Bobrovinitchii Guerold Sergueevitch , Filgueira Marcello
Published: October 2010

Nanometric powders of WC with 10 weight% Co were mixed in high-energy mill. Compaction was performed at 200MPa and processed by the technique of high pressure and high temperature (HPHT). Sintering conditions were P = 5GPa, T = 1300-1400-1500° C, t = 2-4 min. For comparative purposes, samples were conventionally sintered at T = 1400° C, t = 45 min, vacuum of 10-2 mbar.
Microstructural Evolution of Ti-10NB and Ti-15NB Alloys Produced by the Blended Elemental Technique
Authors: Martins G.V. , Silva Cosme Roberto Moreira , Nunes C.A. , Henriques Vinicius André Rodrigues , Borges L.A. , Machado João Paulo Barros
Published: October 2010

Alfa/beta titanium alloys have been intensely used for aerospace and biomedical applications. Production of powder metallurgy titanium alloys components may lead to a reduction in the cost of parts, compared to those produced by conventional cast and wrought (ingot metallurgy) processes, because additional working operations (machining, turning, milling, etc.) and material waste can be avoided. In this work, samples of Ti- 10, 15Nb (weight%) alloys were obtained by the blended elemental technique using hydride-dehydride (HDH) powders as raw material, followed by uniaxial and cold isostatic pressing with subsequent densification by sintering carried out in the range 900–1500 °C. These alloys were characterized by X-ray diffractometry for phase composition, scanning electron microscopy for microstructure, Vickers indentation for hardness, Archimedes method for specific mass and resonance ultrasound device for elastic modulus. For the samples sintered at 1500°C it was identified  and  phases. It was observed the influence of the sintering temperatures on the final microstructure. With increasing sintering temperature, microstructure homogenization of the alloy takes place and at 1500 °C this process is complete. The same behavior is observed for densification. Comparing to the Ti6Al4V alloy properties, these alloys hardness (sintered at 1500 °C) are near and elastic modulus are 18% less.
Comparison of Particle-Wall Interaction Boundary Conditions in the Prediction of Cyclone Collection Efficiency in Computational Fluid Dynamics (CFD) Modeling
Authors: Valverde M.Ramirez , Coury José Renato , Gonçalves José Antônio Silveira
Published: October 2010

In recent years, many computational fluid dynamics (CFD) studies have appeared attempting to predict cyclone pressure drop and collection efficiency. While these studies have been able to predict pressure drop well, they have been only moderately successful in predicting collection efficiency. Part of the reason for this failure has been attributed to the relatively simple wall boundary conditions implemented in the commercially available CFD software, which are not capable of accurately describing the complex particle-wall interaction present in a cyclone. According, researches have proposed a number of different boundary conditions in order to improve the model performance. This work implemented the critical velocity boundary condition through a user defined function (UDF) in the Fluent software and compared its predictions both with experimental data and with the predictions obtained when using Fluent’s built-in boundary conditions. Experimental data was obtained from eight laboratory scale cyclones with varying geometric ratios. The CFD simulations were made using the software Fluent 6.3.26.
Quantitative Determination of the Crystalline Phases of the Ceramic Materials Utilizing the Rietveld Method
Authors: Kniess C.T. , Prates P.B. , de Lima J.C. , Kuhnen N.C. , Riella Humberto Gracher , Maliska A.M.
Published: October 2010

Ceramic materials have properties defined by their chemical and micro-structural composition. The quantification of the crystalline phases is a fundamental stage in the determination of the structure, properties and applications of a ceramic material. Within this context, this study aims is the quantitative determination of the crystalline phases of the ceramic materials developed with addition of mineral coal bottom ash, utilizing the X ray diffraction technique, through the method proposed by Rietveld. For the formulation of the ceramic mixtures a {3,3} simplex-lattice design was used, giving ten formulations of three components (two different types of clays and coal bottom ash). The crystalline phases identified in the ceramic materials after sintering at 1150oC during two hours are: quartz, tridimite, mullite and hematite. The proposed methodology utilizing the Rietveld method for the quantification relating to crystalline phases of the materials was shown to be adequate and efficient.
Processing of AISI M2 HSS with Addition of NbC by Mechanical Alloying Using two Different Types of Attritor Mills
Authors: de Araújo Filho Oscar Olimpio , das Neves Maurício David Martins , Gonzalez Cezar Henrique , Filho U.S.L. , Ambrozio Filho Francisco
Published: October 2010

The processing of a molybdenum AISI M2 high speed steel with the addition of NbC (6% in mass) by a Powder Metallurgy technique of Mechanical Alloying is the aim of this work. Mechanical Alloying (MA) has been used primarily for particle size reduction, to its present status as an important method for the preparation of either materials with enhanced physical and mechanical properties or, indeed, new phases, or new engineering materials. In this work, niobium carbide (NbC) was added to the AISI M2 HSS powders by Mechanical Alloying technique in two different types of attritor mills and the materials which resulted were characterized by means of SEM plus EDS. The powders were processed in a horizontal attritor Zoz mill and in a vertical attritor mill developed in our laboratory. The parameters of milling were distinct and the results of the processing were compared.
Sintering of B4C by Pressureless Liquid Phase Sintering
Authors: da Rocha Rosa Maria , de Melo Francisco Cristóvão Lourenço
Published: October 2010

The effect of three different sintering additive systems on densification of boron carbide powder was investigated. The sintering additives were Al2O3:Y2O3, AlN:Y2O3 and BN:Y2O3 compositions. Powder mixtures were prepared with 10 vol% of sintering aids following conventional powder technology processes. Samples were sintered by pressureless sintering at 2050 °C/30min in argon atmosphere. Sintered samples were compared to a sintered B4C without sintering additive. Samples were characterized by XRD to analyze the crystalline phases after sintering and SEM to observe the microstructure and the second phase distribution. YB4 and YB2C2 were identified in all samples, indicating a reaction between Y2O3, B4C and B2O3 present at the B4C particle surface. The best densification result was achieved with Al2O3:Y2O3 additive system, showing 92.0 % of theoretical density, low porosity and 15.2 % of linear shrinkage. But this sample showed the highest weight loss.
Effect of Hydrogenation Pressure on Microstructure and Mechanical Properties of Ti-13Nb-13Zr Alloy Produced by Powder Metallurgy
Authors: Duvaizem José Hélio , Galdino Gabriel Souza , Bressiani Ana Helena A. , de Faria Jr. Rubens Nunes , Takiishi Hidetoshi
Published: October 2010

The effects of the hydrogenation stage on microstructure and mechanical properties of Ti-13Nb-13Zr alloy produced by powder metallurgy have been studied. Powder alloys have been produced by hydrogenation with 250 MPa or 1 GPa and via high energy planetary ball milling. Samples were isostatically pressed at 200 MPa and sintered at 1150 °C for 7, 10 and 13 hours. Elastic modulus and microhardness were determined using a dynamic mechanical analyzer (DMA) and a Vickers microhardness tester. Density of the samples was measured using a liquid displacement system. Microstructure and phases presents were analyzed employing scanning electron microscopy (SEM). Elastic modulus was 81.3  0.8 and 62.6  0.6 GPa for samples produced by 250 MPa and 1 GPa hydrogenation, respectively when sintered for 7h.
Cobalt-Based Binders and the Efficiency of Diamond Saw Blades
Authors: Bobrovinitchii Guerold Sergueevitch , Filgueira Marcello , Monteiro Sérgio Neves , Tardim Rômulo Crespo
Published: October 2010

Powder metallurgy-based technologies of saw blades production for stone cutting normally uses cobalt as binder agent. Cobalt was chosen for that purpose because it provides improved properties, high wettability and good adhesion between dispersed diamond particles. In addition to its excellent physical properties, cobalt also shows a positive behavior associated with the control of diamond graphitization at temperatures up to 1000°C. In this work, an experimental planning method supported by a mathematical algorithm was used to study the influence of doping agents incorporated into cobalt-based binders. The consequences on the wear resistance of saw blades, as well as on other physical and mechanical properties of the “diamond-cobalt-doping agent” composites were investigated. Cr3C2, Si, Ni and Fe were used as doping agents. Experimental tests were carried out using granite as a base material for wear and cutting operations.
Characterization of HDH Titanium Powder for Biomaterial Applications
Authors: Barbosa Luzinete Pereira , Salgado Lucio , Karsokas N.Filho , Nagamine Márcia Kazumi
Published: October 2010

Several materials have been used as surgical implants since the 16th century. Materials can be implanted in the human body; however, the choice of the appropriate material is based on the required mechanical, physical, chemical, and biological properties. Until now two classes of metals namely stainless steel and cobalt-chromium-molybdenum alloys became known as materials for implant applications. They were considered suitable for surgical implant procedures but many researchers and surgeons were not completely satisfied with their performance. The main problem of the modern science is to find a material that perfectly restores tissues damaged after accidents or diseases. The trend of the current research in orthopedic prosthesis is based on the development of titanium alloys composed of non-toxic elements with low modulus of elasticity. Powder metallurgy techniques have beenused to produce controlled porous structures such as the porous coating applied for dental and orthopedic surgical implants which allows bone tissue grown within the implant surface, improving fixation. The development of porous metallic biomaterials associated with their biomedical applications is an important research area. To obtain a good one implant successful therapy the composition, size, form and topography of the alloys are extremely important.
Gelcasting of Stainless Steel Powder: An Alternative to Injection Molding
Authors: Ortega Fernando dos Santos , Oliveira R.L.S. , Plínio M.C. , Nobrega Bernardo N.
Published: October 2010

The gelcasting process is a forming technique originally developed for the shaping of advanced ceramics into final products in attempts to overcome some of the limitations of conventional forming techniques used in powder metallurgy. It is based on preparing a high solids loading suspension of powder dispersed in an aqueous organic monomers solution, which is poured into a mold and gelled through a chemically initiated polymerization. This work describes the gelcasting of HK-30 stainless steel, a type of powder commonly processed by injection molding. Large (70 x 30 mm) and geometrically complex green compacts with outstanding form retention and stability were obtained. Sintered parts showed good surface finishing and reached 96% of theoretical density, yield strength of 418.5 MPa, and ultimate strength of 701.5 MPa. These results compare favorably with those typically obtained through conventional powder injection molding of HK-30 feedstocks. They support the growing view that gelcasting may soon become an industrial, low cost alternative for near net shaping metallic powders into small or large parts with complex geometries
Study through Potentiodynamic Techniques of the Corrosion Resistance of Different Aluminium Base MMC´s with Boron Additions
Authors: Abenojar J. , Bautista Asuncion , Guzmán S. , Velasco Francisco , Martinez M.A.
Published: October 2010

This paper compares wrought aluminium with PM aluminum and PM aluminium alloys with boron-base additions, containing boron carbide and Fe/B (obtained by mechanical alloying during 36 hours from a Fe-B 50% mixture by weight). The effect of sintering temperature for the Fe/B containing material and the effect of mechanical alloying for the boron carbide containing aluminium alloy on the corrosion resistance of those materials have been studied. Their behavior is followed through cyclic anodic polarization curves in chloride media. In the Al+20%Fe/B composite, low sintering temperatures (650-950°C) exert a negative effect. However, when the material was sintered at high temperature (1000-1100°C) its behaviour was very similar to the PM pure aluminium. The effect of mechanical alloying studied in aluminium with boron carbide was also important in corrosion resistance, finding a lower corrosion rate in the mechanically alloyed material.
Investigation on the Corrosion Resistance of PIM 316L Stainless Steel in PEM Fuel Cell Simulated Environment
Authors: de Oliveira Mara Cristina Lopes , Costa Isolda , Antunes Renato Altobelli
Published: October 2010

Bipolar plates play main functions in PEM fuel cells, accounting for the most part of the weight and cost of these devices. Powder metallurgy may be an interesting manufacturing process of these components owing to the production of large scale, complex near-net shape parts. However, corrosion processes are a major concern due to the increase of the passive film thickness on the metal surface, lowering the power output of the fuel cell. In this work, the corrosion resistance of PIM AISI 316L stainless steel specimens was evaluated in 1M H2SO4 + 2 ppm HF solution at room temperature during 30 days of immersion. The electrochemical measurements comprised potentiodynamic polarization and electrochemical impedance spectroscopy. The surface morphology of the specimens was observed before and after the corrosion tests through SEM images. The material presented low corrosion current density suggesting that it is suitable to operate in the PEM fuel cell environment.
Influence of Silane Films in the Zinc Coating Post-Treatment
Authors: da Costa Marlla Vallerius , Oliveira Cláudia Trindade , Bonino Jean Pierre , Menezes Tiago Lemos , Malfatti Célia Fraga , Müller Iduvirges Lourdes
Published: October 2010

The sol-gel process based on silanes precursors appeared in recent years as a strong alternative for post-treatment to provide an optimization of the protective efficacy of zinc. Moreover, this process has been used to replace chemical chromating conversion based on hexavalent chromium. The silane films are hybrid compounds that provide characteristics of both polymeric materials, such as flexibility and functional compatibility, and ceramic materials, such as high strength and durability. The present work aimed to evaluate the influence of silane films obtained by dip-coating, on the characteristics of electrodeposited zinc coatings. The xerogel films showed a homogeneous surface and a better performance on the corrosion resistance than zinc coating without post-treatment, what can be confirmed by the electrochemical impedance results. These tests showed that application of the silane film promotes the occurrence of one more time constant compared to pure zinc system, hindering the corrosion process.
Creep Behavior of the Titanium Alloy with Zirconia Plasma Sprayed Coating
Authors: Reis Danieli A.P. , de Moura Neto Carlos , Barboza M.J.R. , Silva H.R. , Silva Cosme Roberto Moreira , Couto Antônio Augusto
Published: October 2010

The proposal of this research has been the study of the plasma spayed coating on creep of the Ti-6Al-4V, focusing on the determination of the experimental parameters related to the first and second creep stages. Yttria (8 wt %) stabilized zirconia (YSZ) (Metco 204B-NS) with CoNiCrAlY ( AMDRY 995C) has been plasma sprayed coated on Ti-6Al-4V substrate. Creep tests with constant load had been done on Ti-6Al-4V coated samples, the stress level was from 250 to 319 MPa at 600 °C. Highest values of tp and the decrease of the second stage rate had shown a better creep resistance on coated sample. Results indicate that the coated sample was greater than uncoated sample, thus the plasma sprayed coating prevent the sample oxidation efficiently.
Comparation between PIII Superficial and Ceramic Coating in Creep Test of Ti-6Al-4V Alloy
Authors: Reis Danieli A.P. , de Moura Neto Carlos , Silva M.M. , Ueda Mario , Oliveira V.S. , Couto Antônio Augusto
Published: October 2010

The objective of this work was evaluating the creep resistance of the Ti-6Al-4V alloy with superficial treatment of PIII superficial treatment and ceramic coating in creep test of Ti-6Al-4V alloy. It was used Ti-6Al-4V alloy as cylindrical bars under forged and annealing of 190oC by 6 hours condition and cooled by air. The Ti-6Al-4V alloy after the superficial treat-ment of PIII and ceramic coating was submitted to creep tests at 600°C and 250 and 319 MPa under constant load mode. In the PIII treatment the samples was put in a vacuum reactor (76x10-3 Pa) and implanted by nitrogen ions in time intervals between 15 and 120 minutes. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. The obtained results suggest the ceramic coating on Ti-6Al-4V alloy improved its creep resistance.