bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron-Carbon Core-Shell Nanoparticles Obtained with Different Conditions of Synthesis
Authors: Lima M.M. , Gonçalves J.P.Z. , Soares C. , Riella Humberto Gracher , Fernandes S.C. , Fiori Márcio Antônio , Silva Lucinao Luiz
Published: July 2017

Core–shell Fe2O3@C nanoparticles are very studied due to its biocompatibility with plant and animals cells and due its special properties of chemical adsorption. Thus, the definition of an easy synthesis method of these nanoparticles is very important to the scientific studies and to future applications of these materials. For example, the properties of these nanoparticles depend of the combination between some processing parameters, as the temperature, time, chemical composition, atmosphere and others. The mass yield of the synthesis processes depend of these parameters and are important information. In this work the effect of temperature and of the concentration of the iron precursor were evaluated on the characteristics of the proposed nanoparticles. The nanostructures of Fe2O3 coated with carbon (Fe2O3@C) were synthetized by adapted co-precipitation hydrothermal rote. In 40.0 ml of distilled water was added 1.800 g of glucose, 6.006 g of urea, 0.500 g of polyethylene Glycol (PEG 1500) and different concentrations of iron nitrate Fe (NO2)3.9H2O and different temperature values were applied. The Fe2O3@C core-shell were characterized by scanning electron microscopy (SEM/FEG), Energy Dispersive Scanning (EDS) and X-ray Diffractions (XRD). Results showed that nanoparticles form clusters with different sizes that are dependent on the temperature values and Fe (NO3)3.9H2O concentration. The core-shell mass has a linear relation with the iron precursor mass and the reaction temperatures influences the microstructure of the core-shell nanoparticles.
Antimicrobial Activity of Chlorhexidine against Multi-Species Biofilm Formation
Authors: do Amaral Escada Ana Lucia , Pereira Cristiane Aparecida , Jorge Antonio Olavo Cardoso , Rosifini Alves Claro Ana Paula
Published: July 2017

In the present work, the efficacy of the Ti–7.5Mo alloy nanotube and Ti–7.5Mo alloy nanotube with chlorhexidine against bacterial biofilm formation was evaluated. Nanotubes were processed using anodization in 0.25% NH4F electrolyte solution. Biofilms were cultured in discs immersed in sterile brain heart infusion broth (BHI) containing 5% sucrose, inoculated with microbial suspension (106 cells/ml) and incubated for 5 days. Next, the discs were placed in tubes with sterile physiological solution 0.9% sodium chloride (NaCl) and sonicated to disperse the biofilms. Tenfold serial dilutions were carried and aliquots seeded in selective agar, which were then incubated for 48 h. Then, the numbers CFU/ml (log 10) were counted and analyzed statistically. Scanning electron microscopy (SEM) on discs with biofilms groups and contact angle was carried out. The results show that there is no difference in bacterial adhesion between of the Ti–7.5Mo alloy nanotube and Ti–7.5Mo alloy nanotube with chlorhexidine.
Effect of NbH Particle Size and Cooling Type on the Microstructure, Phase Composition and Microhardness of Ti-20Nb-20Zr Alloy
Authors: Mendes Marcio W.D. , Mendes Narayanna Marques Ferreira , Bressiani Ana Helena de Almeida , Bressiani José Carlos
Published: July 2017

Titanium alloys are widely used as implants in orthopedics and dentistry due to their properties such as high strength, corrosion resistance, biocompatibility and good fatigue resistance. Alloys composed of non-toxic elements, like Nb and Zr, provide lowest Young’s modulus with values near to human bone modulus. The goal of this work was to study the effect of NbH particle size and cooling type on the microstructure, phase composition and microhardness of Ti-20Nb-20Zr alloy. The powders were produced by hydrogenation method. Two different powders of NbH were prepared: powders comminuted (C) and comminuted followed by milling (C+M). After, the alloy powders were milling and homogenizated for 6 h / 300 rpm and sintered at 1300 °C / 3h followed furnace cooling. Afterward, the specimens were treated at 1000 °C / 1 h and cooling in air and water. The samples were characterized by XRD, SEM and Vickers microhardness. The results showed that the alloy is classified as α + β. Vickers microhardness of Ti-20Nb-20Zr ranged between 680-700 and 540-600 HV from alloys prepared with NbH-comminuted and NbH comminuted + milled, respectively. Results indicated that NbH agglomerate behave as barriers for the sintering process of the alloy.
Study on Processing and Characterization of Calcium Phosphate Bioceramics
Authors: Cóta Lívia Fernandes , Lunz Juliana do Nascimento , Ribeiro Alexandre Antunes , Alonso Lizette Morejón , de Oliveira Marize Varella , Pereira Luiz Carlos
Published: July 2017

The calcium phosphate bioceramics are widely used for the bone reconstruction because of their mineralogical similarities. This work aimed to obtain a biphasic calcium phosphate from hydroxyapatite nanoparticles synthesized by sonochemical technique and processed under two different conditions. The samples were uniaxially cold-pressed at 200MPa and sintered at 900°C/2h (CP900) and 1000°C/2h (CP1000) with heating rates of 2°C/min and 5°C/min, respectively. The characterizations were performed by X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and theoretical elastic modulus. From the geometric method, the relative density, porosity and linear shrinkage were measured. The results showed that the studied processing conditions were useful for achieving samples formed by a biphasic calcium phosphate with 80% β-tricalcium phosphate and 20% hydroxyapatite. The CP900 and CP1000 samples presented a theoretical elastic modulus of 34.7 GPa and 53.1 GPa, respectively, which are higher than that found to the compact bone. In addition, the sintering at 900oC was sufficient to promote neck formation and particle coalescence, maintaining adequate porosity (47.5%) for bone tissue ingrowth into pores.
Deformations Limits Analysis of Sheet Metal Manufatured through the Incremental Forming Process
Authors: Gomes Hugo Dutra , dos Santos Freitas Maria Carolina , Moreira Luciano Pessanha , Vitoretti Flavia de Paula , de Castro Jose Adilson
Published: July 2017

The present study is primarily engaged in the implementation of the incremental stamping process in a computerized numeric control This paper presents two different approaches to this forming process, an experimental and other numerical. Experimental used by the computer numerical control to perform the printing process and performs numerical simulations of the process using the finite element method. Some parameters are analyzed in both approaches, such as product geometry effects, tool geometry, tool speed, tool path, contact conditions and mechanical properties of the materials.
Wettability Study of Red Ceramic and Glaze from Dimension Stone Waste
Authors: Rosetti Maria Vitória Machado , Carvalho R.A. , Taguchi S.P. , Borges L.A.
Published: July 2017

The dimension stone industry produces large amount of residue. An alternative to reduce this environmental liability is to apply as glaze in coating ceramic. This research is about the wettability between glaze and red ceramic, applying the sessile drop method. The waste and additives were mixed, pressed, and put over red ceramic plate previously sintered. The system was heated until the melting point of the glaze and the contact angle decreasing was measured in function of the temperature, and in a function of the time at 750 °C and 800 °C. The minimum contact angle value was near 6 ° at 994 °C in the testing changing the temperature, and presents 19 ° and 10 °, respectively, at 750 °C and 800 °C, when the time was varied. The longitudinal section of the samples was analyzed using optical microscopy, showing physical wettability in all testing. This glaze presents good wettability on red ceramic with potential as coating ceramic.
Phase Transformations in Mechanically Alloyed and Sintered Ti-XMg-22Si-11B (X = 2 and 7 at.-%at) Powders
Authors: Maruya Luiz Otávio Vicentin , Fernandes Bruno Bacci , Ueda Mario , Ramos Alfeu Saraiva
Published: July 2017

This work reports on effect of magnesium addition on the Ti6Si2B stability in Ti-xMg-22Si-11B (x = 2 and 6 at.-%) alloys prepared by high-energy ball milling and subsequent sintering. Ball milling was conducted under Ar atmosphere in stainless steel vials and balls, 300 rpm, and a ball-to-powder weight ratio of 10:1. Following, the powders milled for 10 h were axially compacted in order to obtain cylinder samples with 6 mm diameter. To obtain the equilibrium structures the green samples were sintered at 1100°C for 4 h under Ar atmosphere. X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry were used to characterize the as-milled powders and sintered samples. Extended Ti solid solution were found in the Ti-2Mg-22Si-11B and Ti-7-Mg-Si-B powders milled for 20 min and 60 min, respectively, whereas an amorphous halo was produced on Ti-2Mg-22Si-11B powders milled for 420 min. The increase of Mg amount in the starting powder mixture has inhibited the Ti6Si2B formation in the mechanically alloyed and sintered Ti-7Mg-22Si-11B alloy.
Synthesis of Nanostructured Tungsten Carbide (WC) from Ammonia Paratungstate-APT and its Characterization by XRD and Rietveld Refinement
Authors: Lima Maria Jose S. , Souto M.V.M. , Souza A.S. , Karimi M.M. , Silva F.E.S. , Gomes Uilame Umbelino , de Souza Carlson P.
Published: July 2017

The carbides of refractory metals like tungsten carbide (WC), tantalum carbide (TaC) and niobium carbide (NbC), has been extensively studied due to their applications in several areas of industry, because of their specific properties; such as high melting point, high hardness, wear resistance, oxidation resistance and good electrical conductivity. The tungsten carbide, particularly, is generally used at hardmetal industries due to its high hardness and wear resistance. New synthesis techniques have been developed to reduce the synthesis temperature of refractory metal carbides using more reactive precursors and gas-solid reactions for carbon reduction. The result is producing pure carbides suitable properties for production of high quality cemented carbides and more selective catalysts. In this work, pure and nanostructured WC was obtained from the ammonium paratungstate hydrate (APT), at low temperature and short reaction time. Hydrogen (H2) and methane (CH4) were used as a reducing gas and carbon source, respectively. The precursor and obtained product were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained by diffraction of X-rays showed that complete reduction and carburization of APT have been took place resulted in pure WC formation. The average crystallite size was in nanometer order reaching values of approximately 20.8 nm and a surface area (BET) of 26.9 m2/g.
Secondary Hardening of an AISI M3:2 High Speed Steel Sinter 23 Hot Isostatic Pressed
Authors: de Araújo Filho Oscar Olimpio , Gonzalez Cezar Henrique , Urtiga Filho Severino Leopoldino , Oliveira C.A.N. , Silva Noelle D’emery Gomes , Ambrozio Filho F.
Published: July 2017

The main aim of this work was to study the behavior of the secondary hardening of AISI M3:2 high speed steel named Sinter 23® produced by powder metallurgy process of hot isostatic pressing (HIP). The M3:2 high speed steel Sinter 23® was submitted to heat treatment of hardening with austenitizing temperatures of 1140 oC, 1160 oC, 1180 oC and 1200 oC and tempering at 540 oC, 560 oC and finally 580 oC. The effectiveness and response of the heat treatment was determined using hardness tests (Vickers and Rockwell C hardness) and had its property of secondary hardness evaluated. The results showed that the secondary hardening peak of Sinter 23® high speed steel (tempering temperature at which maximum hardness is attained) is at 540 °C for the lower austenitization temperatures of 1140 °C and 1160 °C, and it is at 560 °C for the higher austenitizing/quenching temperatures of 1180 °C and 1200°C.
Heat Treatment and Microstructural Studies of LaNi-Type Battery Electrode Alloys
Authors: Ferreira Eliner Affonso , Barbosa Lusinete Pereira , Faria R.N.
Published: July 2017

The effects of annealing on the microstructures and electrochemical characteristics of a La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8 hydrogen storage alloy have been studied. The heat treatment by vacuum annealing was carried out at 700 °C, 800 °C, 900 °C and 1000 °C. The microstructure and phase composition of the alloy have been investigated using inductively coupled plasma - atomic emission spectrometry (ICP-AES), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction analysis (XRD). The battery anode was prepared using a mixture of the pulverized alloy with carbon black and polytetrafluoroethylene as a binder.
Evolution of Sintering of Particles that Compose Iron Ore Agglomerates
Authors: Vitoretti Flavia de Paula , dos Santos Freitas Maria Carolina , Hosken Camila Martins , de Castro Jose Adilson , da Silva Fabiane Roberta Freitas
Published: July 2017

The increasing demand for new technologies in the ironmaking/steelmaking field has been motivating several studies towards pelletizing process improvement. Within this context, evaluate the reduction of iron ore pellets using the dilatometer technique constitutes a promising approach for optimizing this process. This paper aims the metallurgical characterization through the sintering of particles in iron ore pellets. With this purpose, some experimental procedures are of concern as follows. Firstly, the kinetic densification of the iron ore pellets is measured using a dilatometer, which heats the samples up at 30 K/min until high temperatures about 1473 K and an isotherm at 10 minutes have been done. Then, the sample is cooled back to room temperature and undergoes a microstructural characterization, with the aid of a scanning electron microscope. At last, the density of the pellets is evaluated, using an Arquimedes Principle and consequently the porosity of the agglomerates. The results indicate the sintering progress of the particles that comprise the pellets as well as reduction the porosity. This behavior is due to the fact that the heat arising from gas induces the partial liquid phase formation and involves the agglomerate particles aiding in the sintering process.
The Effect of Heat Treatment on Microstructure and Mechanical Properties of Ti-8.5Nb-4.5Ta-13Zr Alloy
Authors: Mendes Narayanna Marques Ferreira , Mendes Marcio W.D. , Bressiani Ana Helena de Almeida , Takiishi H.
Published: July 2017

The effects of the heat treatment on the phase transformations, microstructures and mechanical properties of Ti-8.5Nb-4.5Ta-13Zr alloy were studies in this work. Some of the starting powder were obtained by hydrogenation method and homogenized with metallic tantalum in a high-energy planetary mill. The samples were compacted in a uniaxial and cold isostatic presses and then, sintered at 1150 °C for 10 hours under high vacuum. The heat treatments were carried out at the same sintering temperature, above the α / β transus, at different cooling rates such as furnace cooling, air cooling and water quenching. The sintered samples were characterized using the Archimedes density method, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microhardness was measured using the Vickers indentation (ASTM E384-11 Standard). It was shown that the microstructure of Ti-8.5Nb-4.5Ta-13Zr alloy consists of beta-phase matrix and alpha-phase region of two structures: equiaxed and needle-like grains also known as Widmanstätten structure. The precipitation of the alpha-phase in the beta-phase matrix led to an increase in Vickers microhardness of the alloy which was furnace cooled. Moreover, a few remaining pores were still found and density above 98% was achieved.
Study of Ceramic Coating Processing Using Dimension Stones Wastes in the Composition of the Glaze
Authors: Hastenreiter L.G. , Santos J.C. , Taguchi S.P. , Borges Jr. L.A. , de Oliveira Gabrielly Sandrine , Sofiati F.W.P.
Published: July 2017

The objective of this work was to produce red ceramic glazed with dimension stone waste. The clay and residue were characterized for crystalline phases (XRD), chemical analysis (XRF) and particle size. Additives were added to the residue in order to reduce the melting point of 1280 oC to 980 °C, because 1100 °C is the temperature typically used in industrial sintering of coating ceramics. It was studied different compositions of glaze and analyzed its viscosity. The engobe and the glaze were applied on the red ceramic, previously pressed with 100x100x5 mm3 size, and sintered at 1100 oC for 1 h, in order to obtain the ceramic coating. These ceramics were analyzed for abrasion resistance, water absorption and chemical attack, according to NBR 13.818/1997, being classified as PEI 1, indicate for use in residential bathrooms and bedrooms without doors outwards, showing the potential use of dimension stone waste for flooring ceramics, mitigating environmental impacts in mineral industry.
Influence of α-Phase Field Heat Treatment on the Tensile and Primary Creep Resistance of a Powder Metallurgical Processed Ti-45Al-5Nb-0.2B-0.2C Titanium Aluminide Alloy
Authors: Marcondes Guimarães Rafael Paiotti , Soyama Juliano , Ebel Thomas , Fredel Márcio C. , Pyczak Florian
Published: July 2017

In powder metallurgical processing the sintering process, as well as heat treatments, can drastically influence microstructure formation. In the case of γ-titanium aluminides, it is critical to achieve certain microstructure parameters, such as colony size, porosity and grain boundary morphology in order to obtain appropriate mechanical properties. In this study, the effect of a heat treatment implemented after sintering with the objective of varying the colony size was investigated. Specimens of Ti-45Al-5Nb-0.2B-0.2C prepared by metal injection moulding and uniaxial pressing of feedstock were used to evaluate the tensile and creep properties. Heat treatments conducted at 1350 and 1400 °C for 3 h led to colony sizes of approximately 100 and 200 μm, respectively. Classically, there is an inverse relationship between grain size and creep resistance, nonetheless, for γ-titanium aluminides, the morphology of the colony boundaries was also found to play a role. The larger colony sizes achieved with the heat treatments did not improve the primary creep resistance, which was explained by the change in the morphology of the colony boundaries as they became larger.
Geopolymeric Cements Obtained by Alkaline Activation of Aluminosilicates from Industrial Waste
Authors: Boca Santa Rozineide A. Antunes , Coelho Leticya Lais , Moreira Jarina Costa , Macuvele Domingos Lusitâneo Pier , Speranzini Larissa M.F. , Riella Humberto Gracher , Kuhnen Nivaldo Cabral
Published: July 2017

The development of geopolymer in this work prioritized the use of industrial wastes including bottom ash from the coal burning and metakaolin from purification and thermal treatment of waste paper. The main objective was the synthesis to obtaining geopolymer cement to verify the characteristics of the material. The alkaline activator used was a mixture of potassium hydroxide (KOH) in molar ratio of 12 and 15 M and sodium silicate (Na2SiO3). X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyzes were performed for characterization. The XRD patterns show changes in the microstructure of the feedstock. Through the micrographs it can be seen that the samples show various aspects of geopolimerization. Geopolymeric materials can be presented as a viable alternative to meet the great demand in the cement area and contribute to the utilization of industrial wastes.
Harmonic Structured Ti6Al4V by Spark Plasma Sintering
Authors: Amorim Lucas de Mello , Vicente Jr. Nério , Berton Marcos Antonio Coelho , Bruno Marino Cláudia Eliana
Published: July 2017

The Ti6Al4V alloy has been applied in situations where mechanical strength, corrosion resistance and biocompatibility are the concern, as in permanent biomedical implants. These material properties are straightly correlated with the microstructure morphology as grain size and crystallographic phases, which is very dependent of the thermal mechanical history and the chemical composition. The Ti6Al4V harmonic structure was primarily achieved by means of Mechanical Ball Milling (MBM) and Spark Plasma Sintering (SPS) using pre-alloyed powder from the plasma rotating electrode processes (PREP). This work aimed at developing the harmonic microstructure by MBM and SPS using pre-alloyed gas atomized powder (GAP). The chemical composition, the microstructure and the hardness were evaluated for the sintered samples and for the commercial wrought annealed conditions, for comparison. The harmonic structure obtained consists of cores containing alpha lath coarse grains surrounded by a three-dimensional network of fine equiaxial grains, while the wrought material shows equiaxial alpha grains in a matrix of beta phase microstructure. The sintered material revealed higher hardness than the wrought alloy.
Effects of the Casting Temperature in the Leakage of Zamak 5
Authors: Marcolin Patrícia , Longhi Marielen , Zini Lucas Pandolphi , Kunst Sandra Raquel , Zattera Ademir José , Fuhr Luciana Taís , Fillmann Tiego V. , Oliveira Cláudia Trindade
Published: July 2017

Recent studies evidenced that the Zamak 5 corrosion is associated to solidification defects arising from the injection process that occur mainly in areas where the solidification rate is faster. Given this factor, the aim of this research was to evaluate the influence of Zamak 5 casting temperature. For this study, Zamak 5 was casted at different temperatures (430 °C, 450 °C, 500 °C, 550 °C) with respective solidification curves. Zamak 5 was analyzed for chemical composition and microstructure. Moreover, complementary tests of microhardness and electrochemical analyses of open circuit potential and polarization were performed. From these analyses it was observed that the highest casting temperature of Zamak 5 originates larger grains and higher microhardness value, due to the lower solidification rate. In none of the leaking temperatures porosity defects were observed on the samples, which is coherent with previous researches, being originated from the injection process.
Sintering Study of NiCrAlY
Authors: Takahashi Renata Jesuina , Assis J.M.K. , Neto Francisco Piorino , Mello A.M. , Reis Danieli Aparecida Pereira
Published: July 2017

In ceramics TBC ́s (thermal barrier coating) the MCrAlY layer is used like a bond coat between nickel superalloys and zirconia ceramics used in aeronautical turbine blades. However the oxidation of this layer is an important step to obtain an Al2O3 as TGO (thermally grown oxide), on which the zirconia ceramics is placed on to protect the turbine blades from high temperatures and oxidizers and corrosive gases generated during the burning of the fuel. To understand the oxidation process, parallel and flat surface samples are required. These surfaces will allow characterization, especially the tribologic ones. The samples were prepared through different process and sintering routes. Powders of NiCrAlY with and without binder were uniaxially pressed from 100 MPa to 250 MPa. Isostatically pressed samples at 300 MPA were also prepared. The samples were sintered in the air, at 10-7 Torr and hot uniaxially pressed at 10 MPa. The sintering temperature started at 800 °C up to 1200 °C during one hour. The best result was from the hot pressed samples between 1000 °C and 1150 °C. Above this temperature the process became complicated and started melting at 1200 oC. Mainly due to the spherical shape of NiCrAlY particles, it was not possible to get good samples when sintering in the air.
Spark Plasma Sintering of Low Alloy Steel Powder
Authors: Schaefer Daniel Auri , da Conceição Leandro , Berton Marcos Antonio Coelho , Ferracin Luiz Carlos , Vicente Jr. Nério
Published: July 2017

Spark Plasma Sintering (SPS) process is a relatively new PM technology used to fabricate metallic parts in shorter time and lower temperature than traditional press-to-sintering technology. In this study, sintering cycles by SPS process were performed in Astaloy CrM steel powder at temperatures between 950 and 1100 °C, with 5 minutes of dwell time and under 60 MPa of uniaxial compaction pressure. The apparent density measured by Archimedes principle, the microstructural investigation by optical microscopy (OM) and scanning electron microscopy (SEM) and the hardness tests by Vicker’s indentation were carried out with the sintered samples. It was observed that at 1050°C more than 98 % of densification was attained. As a low alloy steel powder sintered by SPS an expected high level of densification by the solid state sintering was achieved while hardness is lower than that expected for the Astaloy CrM when sintered mixed with graphite particles.
Effects of Milling Time on Microstructure and Mechanical Properties of Composite WC-(Fe3Al-B) Consolidated by Spark Plasma Sintering
Authors: Ybarra Luis Antonio C. , Chimanski Afonso , Pereira Gilberto J. , Machado Izabel Fernanda , Yoshimura Humberto Naoyuki
Published: July 2017

Cobalt is widely used to produce WC-Co hard metals, but this binder has problems of shortage and unstable price. In this work, cobalt was replaced by an iron aluminide intermetallic binder. WC-10%(Fe3Al-3%B) composite was prepared by vibration milling of WC, Fe, Fe-B, and Al powders and sintered by spark plasma sintering (SPS) at 1150 °C for 8 min under 30 MPa. The milling time was 0.17, 12, 25 and 50 h. The SPS was efficient to consolidate the composite resulting in relative density of ~98% or higher. With increasing milling time, Vickers hardness (HV30) of composite increased from 12 to 14 GPa due to the enhanced homogeneity of microstructure, while the fracture toughness, KIc, determined by an indention fracture method using Shetty equation, remained constant at around 9.1 MPa.m1/2.
Mechanical Alloying and Sintering of Ni-Sn and Ni-Mg Powder Mixtures
Authors: da Cruz Faria Gabriel Henrique , Magalhães Ricardo Boueri , Zanardo Andrezza Campos , Ramos Erika Coaglia Trindade , Pinto da Silva Antonio Augusto Araújo , Coelho Gilberto Carvalho , Ramos Alfeu Saraiva
Published: July 2017

Various intermetallics can be synthetized by mechanical alloying depending on alloy composition, type of mill, and milling parameters. This work discusses on the phase transformations during ball milling and subsequent sintering of Ni-Sn and Ni-Mg powder mixtures. The structural evaluation of as-milled and sintered samples was conducted by X-ray diffraction and scanning electron microscopy. Metastable phases were formed during milling of the Ni-Sn and Ni-Mg powder mixtures. The Ni3Sn and Ni3Sn2 compounds were produced after sintering from the as-milled Ni-25Sn and Ni-40Sn powders, respectively. Two-phase Ni2Mg+NiMg2 alloy was found after sintering of as-milled Ni-66Mg powders because the nominal Mg amount in starting powders was reduced due to its preferential cold welding during milling and/or evaporation during sintering.
Structural Evaluation of Ti-Cr-Si-B Powders Produced by High-Energy Ball Milling and Sintering
Authors: Maruya Luiz Otávio Vicentin , Suzuki Paulo Atsushi , Ramos Alfeu Saraiva
Published: July 2017

Multicomponent Ti6Si2B-based alloys are potentially attractive for structural applications due to the low Ti6Si2B crystallographic anisotropy, and their oxidation resistance are higher than the Ti5Si3-based alloys. There is a limited amount of information on effect of alloying on stability of Ti6Si2B. The present work reports on the structural evaluation during ball milling and subsequent sintering of Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B (at-%) powders. The milling process was carried out in a planetary Fritsch P-5 ball mill under Ar atmosphere using hardened steel balls (19 mm diameter), stainless steel vials (225 mL), rotary speed of 300 rpm, and a ball-to-powder weight ratio of 10:1. Samples were collected after different milling times: 20, 60, 180, 300, 420 and 600 min. Addicional wet milling (isopropyl alcohol) for 20 more minutes was adopted to increase the yield powder into the vials. Following, the powders milled for 620 min were uniaxially compacted (20 MPa) in order to obtain cilinder green bodies with 10 mm diameter and subsequently sintered under vacuum at 1100°C for 240 min. The milled powders were characterized by X-ray diffraction, and scanning electron microscopy. The chromium addition have contributed to form a large amount of Ti6Si2B in the mechanically alloyed and sintered Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B alloys.
Influence of Grinding Media Size and Sintering Time in the Processing of AISI D2 Tool Steel by High-Energy Milling
Authors: Vurobi Jr. Selauco , Hupalo Marcio Ferreira , Namur Ricardo Sanson , Fernandes Thiago Augustin Lucas , Cintho Osvaldo Mitsuyuki
Published: July 2017

Tool steels are fundamental in the current production processes, as they are used in dies and molds, essential for the transformation of raw materials into the final product. The tool steels for cold work have a low hot hardness, so their use is limited to temperatures below 200° C. The D-X series of tool steels, high carbon and high chromium, have a high wear resistance and is much used in the manufacture of dies and molds. Despite the high hardness, these steels have a microstructure with coarse carbides, which affects the hardness of the material. An alternative to the processing tool steels is the high-energy milling and subsequent powder metallurgy, in order to refine the microstructure of the material. This work aimed to study the influence of the size of the grinding media in the refining of the microstructure of AISI D2 by high-energy milling and the microstructural changes with the increase in sintering temperature. The results indicated that grinding media of smaller diameters had higher efficiency in high-energy milling due to smaller mean particle size obtained by grinding and subsequent final reduction in the average size of carbides. The sintering time had a direct influence on the microstructure of the material, higher sintering times led to formation of lower bainite, after cooling from sintering temperature.
Fundamentals of Microwave Heating and Drying of Drilled Cuttings
Authors: Rossi Arley Silva , Pereira Marina Seixas , dos Santos Jéssika Marina , Petri Jr. Irineu , Ataíde Carlos Henrique
Published: July 2017

Drilled cuttings contaminated by non aqueous drilling fluids are the major waste from oil well drilling activities. More restrictive environmental legislation has led to the search for alternative technologies to promote cuttings decontamination according to the law. The mixture of cuttings and fluid returning from the well goes through a set of separation equipments, called solids control systems, in order to recover the drilling fluid for reuse. The cuttings from the solids control system must be decontaminated before they can be discharged into the sea. Microwave heating has been studied over the past few years as an alternative to promote the decontamination of this waste and has been shown to be a promising technology. This work aimed to investigate fundamental aspects of microwave heating and drying of drilled cuttings. The heating curve of two different drilling fluids commonly employed in well-drilling operations was obtained. The kinetics of drying of cuttings contaminated with these drilling fluids was also investigated. It was evaluated the behavior of organic phase and water removal in the microwave drying process.
Mechanical Properties and Microstructural Characterization of Cobalt-Chromium (CoCr) Obtained by Casting and Selective Laser Melting (SLM)
Authors: Mergulhão Marcello Vertamatti , Podestá Carlos Eduardo , das Neves Mauricio David Martins
Published: July 2017

The aim of this study is the consolidation of Cobalt-Chromium (CoCr) alloy powder using the additive manufacturing - selective laser melting (SLM) and the investment casting techniques. The research of this study has been applied to their biomaterial applied to development of prosthesis and dental implants. The gas atomized powder are spherical (mean diameter equal to 42,74 μm) and was analyzed by their physical and chemical properties. The microstructure of the powder and specimens was evaluated using optical microscope (OM) and scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS). The mechanical properties were evaluated of standard samples using a tensile (yield strength, maximum tensile, rupture tensile and elongation), three point bending (transverse rupture strength) and micro hardness tests. The mechanical results indicate higher values for the SLM than casting specimens. The micrographs revealed a characteristic morphology of laser been used in the SLM technique and the dendrites in the casting technique. The microstructure of samples made by SLM is thinner than the samples obtained in the cast.
Study of the Encapsulations of the Eugenol in β-Cyclodextrin in Low Concentrations Conditions
Authors: Piletti Raquel , Bugiereck A.M. , Pereira A. , Mello J.M.M. , Dalcanton F. , Ternus R. , Dal Magro J. , Riella Humberto Gracher , Fiori Márcio Antônio
Published: July 2017

Essential oils, their antimicrobial properties due to arouse interest in the food industry for use as antimicrobial additives. However, due to their low thermal and oxidative stability its application is limited. Among the essential oils, eugenol is a compound already used studied due to their numerous properties. To minimize the degradative effects resulting from environmental factors or thermal processing, one possibility is the formation of inclusion complexes with β-CD in order to increase their thermal stability and provide controlled release. The objective of this study was to obtain and characterize β-CD-eugenol microcapsules obtained in solutions containing low concentrations of Eugenol compound. The result showed the formation of the microcapsules but with low antibacterial actions due the low concentration of Eugenol in the complexes. The encapsulations constant (Kc) determined is 27.62 M-1 and the FTIR spectra indicated the microencapsulation.
Dry and Wet Milling Comparison of Nd-Fe-B Magnets Based on Strip Cast Alloys
Authors: Maccari Fernando , Well R.V. , Eller G. , Hoffmann M.S.T. , Lopes Leonardo Ulian , Takiishi H. , Wendhausen Paulo Antônio Pereira
Published: July 2017

In this work, the influence of milling medium was investigated in order to achieve high energy-product Nd-Fe-B magnets, mostly by the remanence improvement related to the obtention of monocrystalline particles during milling. Nd-Fe-B alloy made by strip-casting process were used as starting material, which exhibits refined grain structure and demands special attention during milling in relation to coarse-grained, conventionally cast alloys. It was found that by using liquid medium during ball milling process, the mean particle size decreased, as well as the size distribution, which improved the particle alignment and hence the remanence in the sintered magnet. Texture was quantified by magnetic characterization based on reference isotropic magnets made in same conditions, and microstructure development was evaluated by optical microscopy. Moreover, after post-sintering treatment, the coercivity increased 20% compared to as sintered state without changing the remanence, providing an anisotropic magnet with high coercivity.
Effect of Compaction Pressure on the Hysteresis Loop of NdFeB Bonded Magnets
Authors: Rodrigues Daniel , Concílio Gilberto Vicente , de Castro Jose Adilson , de Campos Marcos Flavio
Published: July 2017

Compression moulded NdFeB bonded magnets can advantageously replace the sintered version in applications that require specific shape and size. The maximum densities that can be obtained for ready-to-press commercial raw materials are close to 6.0 g/cm3. For large pieces, uniaxially pressed, densities should be limited to values as 5.0 g/cm3 due to the friction during compression. This paper investigate the effects of final density (ranging from 5.0 to 6.0 g/cm3) on the magnetic of compression moulded magnets. A ready-to-press Magnequench MQPB+ was used as raw material. Small cylindrical samples were produced by press and cure. Results are presented and discussed considering aspects related to relative densities. The magnetic properties are dependent of density, and coercivity decreases with deformation during compaction.
Experiments and CFD Predictions of Particles Velocity and Trajectory in Flow with Non-Newtonian Fluid through a Partially Obstructed Duct
Authors: Bicalho Isabele Cristina , dos Santos Dyovani Bruno Lima , Ataíde Carlos Henrique , Duarte Claudio Roberto
Published: July 2017

Dynamic of particles in annular fluid flow is a very relevant subject for many industrial applications, especially for the oil and gas industry. Successful drilling is, to a large extent, dependent upon the ability of the drilling fluid to clean the hole by conveying the cuttings to the surface. The aim of this work was to evaluate experimentally and through numerical simulations, the helical path and the axial mean velocity developed by glass beads with diameter of 2.7 mm flowing with a non-Newtonian fluid through a partially obstructed annulus. Experimental data are reported for flow of 1 m3/h of an aqueous solution with 0.5% Xanthan gum through concentric annulus with partial obstruction of 6 mm and a 183 rpm rotation of the inner cylinder. Techniques of computational fluid dynamics (CFD) were applied to obtain detailed information about the flow field, allowing to estimate the radial position of launching of particles in the range of 35.5 mm to 39.1 mm. Comparisons between numerical calculations and the flow data indicated, in general, a very good agreement.
CFD Simulation of Different Flow Regimes of the Spout Fluidized Bed with Draft Plates
Authors: Araújo Bruna Sene Alves , dos Santos Kássia Graciele
Published: July 2017

Spout fluidized bed has shown promising for gas-solid contact operations with and without chemical reactions, such as drying, coating, granulation, gasification, pyrolysis, etc. This is because these beds combine features from both spouted and fluidized beds. The other point is the ability to treat chemical transformations involving both heat and mass transfer in combination with particles of various sizes. Therefore, it is extremely important the knowledge of fluid dynamic of the bed, mainly for scale-up projects, which makes computer simulation an essential tool. Researches using the Computation Fluid Dynamics (CFD) proved to be very effective in predicting of particles dynamic in this type of bed. In Computation Fluid Dynamics, the two phases are treated as interpenetration continuous, and these phases are described by equations of conservation of mass, momentum and energy. The goal of the present work was to simulate using CFD experimental fluid dynamics data of a spout fluidized bed. Eight distinct flow regimes were identified which showed up in good agreement with the regime map presented in literature. The results showed that the technique was efficient for the simulation of the hydrodynamic of the bed presented.
Geochemical assessment of lake sediments in protected areas in Poland – a search for reference condition
Authors: Cieślewicz Joanna , Kobierski Mirosław , Cichosz Marcin
Published: July 2017

This paper presents the results of an assessment of macro- and microelements in the sediments of lakes laying within protected areas in Poland – the Drawa National Park, the Wel Landscape Park and the Górzno-Lidzbark Landscape Park. In each lake two grab sediment sample were collected: one in the littoral zone and the other in the deepest part of the lake basin. Sediment samples analysed for their content of inorganic carbon (IC) and the loss on ignition (LOI at 550°C) and, according to these parameters classified into three sediment types. Micro elements were detected with SEM-EDX system and the bioavailability of Zn, Cu, and Fe was evaluated after an extraction with DTPA (diethylenetriaminepentaacetic acid) solution. The most diverse chemical composition of the sediments was observed in the lakes of the Wel Landscape Park Lacustrine sediments were characterized by the heterogeneous content of organic matter (from 11.70 to 52.89%), calcium carbonate (from 0.0 to 42.73%) and mineral fractions (from 38.24 to 79.46%). They consisted of three different types of gyttja (fine grain-size, clayey-calcareous, clayey). The highest content of trace elements was determined in fine grain-size gyttja, which results from their current sorption properties, as well as alimentation by river waters flowing into the lakes. 
The sediments contained relatively low concentrations of the analysed elements, which was reflected in the low values of the contamination factor (CF), the contamination degree (Cdeg), the geo-accumulation index (Igeo) and the enrichment factor (EF). Values of the Igeo point out also that these lake sediments were not contaminated by heavy metals. The total content of zinc and copper in some analyzed sediments was higher than the content assumed as acceptable for protected areas. The contribution of bioavailable forms of Zn and Cu ranges from 2.3 to 29.1% for Zn, and from 4.6 to 18.4% for Cu. The type of sediment, and the surface area largely determined the lake sediment chemical composition, while land-use in the catchments had a minor effect. This applies to both lakes of different parks and lakes within each of the parks.
Organic matter dynamics in a savanna transition riparian zone: input of plant reproductive parts increases leaf breakdown process
Authors: Rezende Renan S. , Correia Patrícia R.S. , Gonçalves Jr José F. , Santos Anderson M.
Published: July 2017

The dynamics of coarse particulate organic matter (CPOM) drives the functioning of most low order freshwater ecosystems. We evaluated plant litter input, litterfall, leaf litter breakdown rates, and the aquatic invertebrate community over the course of one year in a stream situation in a transition zone between savannah and Atlantic forest. Total organic matter input (litter fall) was 335 g m-2 yr-1, which was mainly composed of leaves (50%). Higher values are found in the transition from dry to rainy season (September and October), probably in response to water stress. The remaining leaf mass (65% on average) was lowest in May (49%) and highest in August (79%). CPOM productivity in this transition riparian zone is higher than in other savannah systems, but lower than in Atlantic forest. The higher leaf litter breakdown in May was likely accompanied by environmental enrichment due to increase in fruits and flowers (high energy resources). The coefficient of decomposition was classified as fast (k= -0.016) and showed a positive relationship with water flow (increase in physical abrasion). Collected invertebrates were classified as 6% shredders and 12% scrapers. The remaining leaf mass showed a negative relationship with scraper abundance, highlighting the importance of these trophic groups in tropical streams. We can conclude that climate factors (e.g., rainfall) directly affect the input and quality of CPOM and, consequently, leaf decomposition in savanna/Atlantic forest transition zones. 
Analysis on the association among stunting, wasting and underweight in Malawi: an application of a log-linear model for the three-way table
Authors: Ngwira Alfred , Munthali Eddons C.S. , Vwalika Kondwani D.
Published: July 2017

Childhood undernutrition is an important public health problem. Many studies have investigated the factors of childhood undernutrition, but not the association between the undernutrition indicators. This study aimed at investigating the association between the childhood undernutrition indicators. A loglinear model of cell counts of a three way table of stunting, wasting, and underweight was fitted based on the 2010 Malawi demographic health survey data. Interaction terms in the model depicted deviations from independence. A multiple correspondence analysis of undernutrition indicators was also plotted to have a visual impression of association of the undernutrition variables. A loglinear model showed that underweight was associated with both stunting (P<0.001), and wasting (P<0.001). There was no association between stunting and wasting (P=1). Furthermore there was no three way association of stunting, wasting and underweight (P=1). Lack of three way interaction of stunting, wasting and underweight means that childhood undernutrition multidimensional nature is still valid, and no each indicator can represent the other.
Why publishing the Journal of Public Health in Africa
Authors: Colizzi Vittorio , Sonela Nelson
Published: July 2017

The population of sub-Saharan Africa faces global health challenges more than any other part of the world, bearing the brunt of tuberculosis, malaria and HIV/AIDS. This region already carries 24% of the global disease burden and the situation is made worst by the advent of noncommunicable diseases, such as coronary heart disease, hypertension, cancer and diabetes (just to name a few). Thus the need for African scientists to disseminate research data in order to alleviate the continent’s huge disease burden and help the frail health systems affected by poverty, underdevelopment, conflicts and poorly managed government agencies. In our opinion, the Journal of Public Health in Africa responds to the need for a communication system aimed at reaching the widest audience of professionals worldwide in a shorter time than traditional publishing [...]
Colonic adenocarcinoma presenting as hemophagocytic syndrome
Authors: Ali Murtaza , Jain Siddharta , Wig Naveet , Biswas Ashustosh , Kumar Arvind , Kumar Kuldeep
Published: July 2017

Hemophagocytic syndrome (hemophagocytic lymphohistiocytosis [HLH]) is a rare and potentially fatal disorder characterized by pathological immune activation associated with primary familial disorder, genetic mutation or occurring as a sporadic condition. The later can be secondary to infections, malignancies, or autoimmune diseases. Malignancy-associated HLH is commonly seen in hematological malignancies and rarely with solid organ tumors. We report a case of adenocarcinoma colon presenting as hemophagocytic syndrome. To the best of our knowledge, it is the first case report of HLH secondary to carcinoma colon.
Malignant intracranial hemangiopericytoma in a 22-year-old male with head injury and implications
Authors: Sharma Mukesh , Thakur Purnima , Fotedar Vikas , Sharma Anjna , Chatterjee Debajyoti
Published: July 2017

We report a case of intracranial hemangiopericytoma of a young male of 22 years who presented with neurological signs of impaired memory, left hemiparesis, headache, and two episodes of focal seizures. A significant history of head trauma 9 years back was given. A space-occupying lesion was identified in the bilateral frontoparietal region. The surgical intervention involved bilateral frontoparietal craniotomy and Simpson Grade II excision of tumor. Postoperative conformal radiotherapy was administered. A marked neurological improvement was subsequently observed. Peak incidence of this disease is in the fourth or fifth decade. However, our case is an exception presenting at an age of 22 years. Associated history of head trauma has only been infrequently reported in the past.