Scielo RSS <![CDATA[Materials Research]]> http://www.scielo.br/rss.php?pid=1516-143920150001&lang=pt vol. 18 num. 1 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[Editorial]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100001&lng=pt&nrm=iso&tlng=pt <![CDATA[Characterization of Calcium Phosphate Coating Produced by Biomimetic Method]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100003&lng=pt&nrm=iso&tlng=pt Titanium and its alloys have been used in dentistry to due their excellent corrosion resistance and biocompatibility. However, titanium coating is bioinert material and it cannot chemically bond to bone tissue. The purpose of this work was evaluating the bioactivity of Ti-7,5Mo alloy after chemical treatment using H2SO4 / H2O2 and soaking in SBF. Samples were chemically treated at room temperature for 4 h with a solution consisting of equal volumes of concentrated H2SO4 (200 ml) and 30% aqueous solution H2O2 (200 ml). The oxidized samples were rinsed with distilled water and were heat treated at 600°C for 1h in a electrical furnace in air. Then, all samples were immersed in SBF (Simulated Body Fluid) for 7 and 14 days to form a calcium phosphate (Ca/P) coating on the surface. Surfaces were characterized by using SEM, AFM and contact angle. The results indicated that calcium phosphate (Ca/P) was formed on surface of Ti-7.5Mo experimental alloy. <![CDATA[Critical Assessment of the Surface Tension determined by the Maximum Pressure Bubble Method]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100009&lng=pt&nrm=iso&tlng=pt The main factors that influence the value of surface tension of a liquid measured with the Maximum Pressure Bubble Method are critically evaluated. We present experimental results showing the effect of capillary diameter, capillary depth, bubble spheroidicity and liquid density at room temperature. We show that the decrease of bubble spheroidicity due to increase of capillary immersion depth is not sufficient to explain the deviations found in the measured surface tension values. Thus, we propose a simple experimental procedure that allows determining the surface tension of a liquid without any previous knowledge of its density. This procedure is especially useful when the liquid of interest exhibits variations of surface tension and density with time, as for example during condensation reactions to obtain SiO2 sols from a tetraethyl ortosilicate (TEOS) solutions during their aging process. <![CDATA[Comparative Sensibility Study of WO<sub>3</sub> ph Sensor Using EGFET and Ciclic Voltammetry]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100015&lng=pt&nrm=iso&tlng=pt In this present study, the investigation about pH sensorial properties of WO3, via sol-gel, was evaluated by Voltammetry and Extended Gate Field Effect Transistor techniques. The X-ray diffractogram indicates the presence of a lamellar structure, d = 0.69 nm, resulting in WO3.2H2O. From Scanning Electron Microscopy of WO3.2H2O was observed a process corresponding to the delamination which consists of irregular stacking with rounded platelets. The WO3.2H2O was investigated as a pH sensor in the pH range 2–12, by the EGFET and Voltametry techniques presenting a sensitivity of 52 mV/pH and 60 mV/pH, respectively. These results can indicate that both Voltammetry and EGFET techniques present values close to the theoretical limit (59.2 mV/pH) as well as the material is a promising candidate for applications as a pH sensor and as disposable biosensor in the future. <![CDATA[Corrosion Behavior of Coarse- and Fine-Grain Ni Coatings Incorporating NaH<sub>2</sub>PO<sub>4</sub>.H<sub>2</sub>O Inhibitor Treated Substrates]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100020&lng=pt&nrm=iso&tlng=pt Plain carbon steel substrates were treated with NaH2PO4.H2O inhibitor for 24 hours and coated with Ni using dc and pulse electrodeposition in standard Watt’s bath. The effect of dc and pulse electrodeposition, on the microstructure and corrosion properties of Ni coatings in 3.5 wt% NaCl solution was studied. The effect of inhibitor on the deposition process and corrosion behavior was also examined. Materials characterization was performed using field emission scanning electron microscopy, cross-sectional scanning transmission electron microscopy, atomic force microscopy, x-ray diffraction and nanoindentation. Experimental results indicated that pulse electrodeposition produced fine grained Ni coatings that showed lower corrosion rate compared to coarse grained dc electrodeposited Ni. Pre-treatment of substrates with inhibitor did not adversely affect the deposition process and adherent Ni coatings were readily developed. The results showed that pulse electrodeposition could be used to produce hard corrosion resistant Ni coatings while the inhibitor treatment yielded enhanced corrosion protection by providing a protective buffer layer between the Ni coating and the substrate. <![CDATA[Acquired Properties Comparison of Solid Nitriding, Gas Nitriding and Plasma Nitriding in Tool Steels]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100027&lng=pt&nrm=iso&tlng=pt Plasma nitriding, gas nitriding and solid nitriding were applied in tool steels (AISI H13, AISI P20 and N-8550). The acquired properties were compared and evaluated on these three processes with the aim to verify the solid nitriding performance. In order to promote the solid nitriding, the samples were surrounded by a solid compound with the Fe4KCN stoichiometric formula, inside an aluminum recipient. All thermochemical nitriding processes were performed at 560 °C. The wear behavior has been assessed by dry sliding wear test, using a pin-on-disk apparatus, the amount of wear was obtained by the use of a profilometer. The wear tracks were analyzed using SEM (Scanning Electron Microscopy). After the wear test the samples were transversally cut, to obtain the Vickers microhardness. Solid nitriding presented good performance, formation of a nitriding layer, values of microhardness compatible with the other processes and the best results of wear. <![CDATA[Study of Pipeline Steels with Acicular Ferrite Microstructure and Ferrite-bainite Dual-phase Microstructure]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100036&lng=pt&nrm=iso&tlng=pt Three kinds of X70 steels with the same chemical composition and different microstructures fabricated by varying processes were compared in aspect of the microstructures and mechanical properties using SEM, TEM and tensile testing machine. The experimental results showed that the steel 1 with acicular ferritic microstructure fabricated by thermal-mechanical processing with online accelerated cooling (TMCP) exhibited an excellent combination of strength and toughness, but provided high yield ratio of 0.85, low uniform elongation of 8.3% as well as low strain hardening exponent of 0.09, indicating poor deformability. In contrast to above steel 1, the steel 2 and steel 3 having ferrite-bainite dual-phase microstructure respectively fabricated by TMCP and intercritical annealing exhibited the improved deformability in terms of the low yield ratio of 0.69 and 0.68, high uniform elongation of 12.8% and 11.8%, and strain hardening exponent of 0.157 and 0.155. It is argued that the optimum properties combination of strength, toughness and deformability can best be achieved by obtaining a ferrite-bainite dual-phase microstructure. This kind of ferrite-bainite dual-phase pipeline steel is appropriate to transmitting oil and natural gas in seismic zone and permafrost. <![CDATA[Evaluation of the Influence of MgO and La<sub>2</sub>O<sub>3</sub> on the Fast Sintering of Mullite]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100042&lng=pt&nrm=iso&tlng=pt The influence of MgO and La2O3 on the fast sintering of mullite was evaluated in this work. High-purity mullite was doped with MgO and La2O3, conventionally sintered, fast sintered, and microwave-sintered in rapid sintering cycles. The results showed that MgO and La2O3 strongly affected the densification of fast sintered samples; and only doped bodies reached high densities when fast sintered. However, the densification behavior of doped samples was dependent on the amount of sintering aids. MgO doped samples presented better densification behavior than La2O3 doped samples. Microwave-processed samples required a balance between power, time and amount of additives to obtain highly dense and homogenous microstructures. <![CDATA[Effect of Low Temperature Nitriding of 100Cr6 Substrates on TiN Coatings Deposited by IBAD]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100054&lng=pt&nrm=iso&tlng=pt In this paper we studied the influence of pre-treating the surface of 100Cr6 steel by ion beam nitriding at low temperature (380°C) on the surface topography and wear resistance of thin TiN coatings deposited by reactive ion beam assisted deposition. The specimens were characterized by grazing incidence X-ray diffraction, scanning electron microscopy and atomic force microscopy. The wear resistance of the TiN-coated specimens was evaluated by means of ball on disc tests. The results showed that application of a preliminary ion beam nitriding treatment slightly increased the surface roughness but improved the wear resistance of the 100Cr6 steel due to the formation of a diffusion zone containing the γ'-Fe4N nitride combined with the TiN coating. <![CDATA[Effect of Continuous and Pulsed Current on the Metallurgical and Mechanical Properties of Gas Tungsten Arc Welded AISI 4340 Aeronautical and AISI 304 L Austenitic Stainless Steel Dissimilar Joints]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100059&lng=pt&nrm=iso&tlng=pt In this research work, the weldability of low alloyed AISI 4340 aeronautical steel and AISI 304L austenitic stainless steel joined by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) techniques, using ER309L and ERNiCr-3 filler metals was investigated. The main focus of the study involves the investigation on the effect of continuous and pulsed current mode of GTA welding process on the metallurgical and mechanical properties of these dissimilar weldments. Microstructure studies revealed the formation of different zones across the weldments, vis-à-vis martensite at the HAZ of AISI 4340, vermicular δ - ferrite /ferrite stringers at the HAZ of AISI 304L, pearlite colonies at the parent metal of AISI 4340 and equi-axed cellular and/or columnar dendrites at the weld zone. Tensile results showed that current pulsing accrued better tensile properties. The structure - property relationships of these weldments were established based on the current modes employed by utilizing combined techniques of optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). <![CDATA[Effect of Post-production Heat Treatment on Particleboard from Sugarcane Bagasse]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100078&lng=pt&nrm=iso&tlng=pt This study aimed to evaluate the effect of heat treatment on the physical and mechanical properties of particleboard from sugarcane bagasse. The experiment consisted of seven treatments arranged in a 2 × 3 factorial arrangement (two heat treatment times – 8 and 12 min, and three heat treatment temperatures – 200 °C, 230 °C, and 260 °C) and treatment control (without heat treatment). We evaluated the properties such as apparent density, water absorption after 2 and 24 h (WA2h andWA24h), thickness swell after 2 and 24 h (TS2h and TS24h), irreversible thickness swelling rate (ITS), internal bond, Modulus of Elasticity (MOE), and Modulus of Rupture (MOR) in static bending. In general, the use of heat treatment appeared very promising for improving the dimensional stability of sugarcane bagasse particleboard, without being made unviable by the mechanical properties reduction. <![CDATA[Microwave Assisted Synthesis and Sintering of Ba<sub>0.5</sub>Sr<sub>0.5</sub>Co<sub>0.8</sub>Fe<sub>0.2</sub>O<sub>3-δ</sub> Perovskite]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100085&lng=pt&nrm=iso&tlng=pt Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite-type oxide is currently one of the most promising materials for applications in solid-oxide fuel cells (SOFCs), protonic ceramic fuel cells (PCFCs), oxygen separation membranes, and catalytic membranes for methane conversion. BSCF powder synthesis has received considerable attention and new synthesis methods have been proposed to obtain nanoscale powders with high chemical homogeneity. In this study, BSCF perovskite powder has been successfully prepared by microwave assisted combustion in aqueous solution. The synthesized powder was characterized by DSC, BET, XRD, and SEM. BSCF powder presented phase homogeneity, high specific surface area (9.93 g/m2) and nanometric crystallite size (23nm). The microwave sintering has been conducted in different conditions of dwell time and temperature. The influence of the temperature and the dwell time on microstructure was evaluated by optical microscopy. The results showed that microwave sintering could achieve the same densification compared to conventional sintering with only 10% of processing time. This shorter processing time has resulted in a reduction of grain size of up to 46.5%, compared to conventional sintering. <![CDATA[Numerical Simulation of Hot Closed Die Forging of a Low Carbon Steel Coupled with Microstructure Evolution]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100092&lng=pt&nrm=iso&tlng=pt Hot closed die forging is a regular process applied to manufacture metallic components used in supporting and fixing cable conductors in electric power transmission lines. In this forming process, the final microstructure of the workpiece depends on the control of several processing parameters. In this study, simulation of the industrial forging process of a ball hook component was performed using the finite element software DEFORM-3D following the thermomechanical procedures coupled with microstructure evolution. This simulation allowed the study of the process parameters such as temperature, strain and strain rate and microstructure evolution during hot closed die forging of a low carbon steel. The geometry and grain size evolutions obtained by simulation are compared with those found in the actual process and measured by optical microscopy. The attained data indicated that the simulation is able to describe processing parameters and microstructure evaluation during hot forging of a metallic component. <![CDATA[Evaluation of the Incorporation of Waste Generated from Titanium Dioxide Manufacturing in Red Ceramics]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100098&lng=pt&nrm=iso&tlng=pt Rotary-vacuum-filter mud (RVFM) is waste generated during the manufacturing process of titanium dioxide. In this work, RVFM and ceramic bricks containing different ratios of this waste are investigated. The mud samples were characterized using thermal analysis (TG/DTG). The aim of the present work was to determine the effect of adding RVFM on the ceramic properties of clay, such as apparent porosity, water absorption, linear shrinkage and flexural strength, used to produce red ceramics (bricks and roofing tiles). Samples were dried out at 110°C and fired at 800°C, 950°C and 1100°C. The addition of RVFM tends to increase the apparent porosity and water absorption and to decrease the flexural strength of the ceramic specimens. Based on the results, ceramic specimens with 20% RVFM content that are burned at 800ºC can not be used as bricks, and ceramic specimens with 20% RVFM content that are fired at 800ºC and 950°C can not used as roofing tiles, according to Brazilian standards. <![CDATA[The Evolution of the Niobium Production in Brazil]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100106&lng=pt&nrm=iso&tlng=pt Niobium (Nb) was initially applied in the industry in 1933 to stabilize stainless steels against intergranular corrosion. Around 1970, niobium started to be used in many technological applications, especially in heat treatments at high temperatures, in the form of superalloys and, over the past four decades, Nb has been employed on an industrial scale. During recent years, applications of niobium have increased steadily in various segments such as: micro-alloyed steels, super alloys, thin films, medical implants, titanium and aluminum alloys, superconductors and copper alloys, electrolytic and ceramic capacitors. The worldwide demand for Nb grew at an annual rate of 10% between the years 2000-2010, were the sectors of energy, automotive and construction of the largest consumers FeNb. In 2000 the brazilian production was 35,458 t of Nb and, in 2007, reached 82,000 t of concentrate Nb. Brazil has the world's largest reserves of Nb (98.53%), which totaled 842.4 million t. So, in this paper is made a study on the evolution of the production of niobium in Brazil and its main industrial and technological applications. <![CDATA[Recovery of α-Al<sub>2</sub>O<sub>3</sub> from Ionizing Radiation Dosimetric Sensors]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100113&lng=pt&nrm=iso&tlng=pt Corundum, sapphire or α-Al2O3 is an important technological material in many optical and electronic applications such as solid-state lasers, optical windows and, more recently, as a radiation detector. Landauer (Glenwood, IL, USA) accumulated large number of archived and stored Luxel™ dosemeters composed of Al2O3:C, which were subjected to a recovery process. Due to the importance of this advanced crystalline material in OSL dosimetry, a recovery process was developed based on the dosemeters calcination and Al2O3:C has been reused in manufacturing of new dosemeters. This paper does not aim to optimize the recovery process, but provides an opportunity to study the involved process parameters and to recover this valuable crystalline material from used dosemeters. To the best of our knowledge no other recovery process involving this dosimetric material was described in scientific literature. Fourier Transform Infrared Spectrometry (FTIR), Thermogravimetry/Differential Thermoanalysis (TG/DTA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Optically Stimulated Luminescence (OSL) and Rietveld Refinement were used to characterize the recovered material and to check for the stability of its structural and dosimetric properties. <![CDATA[Evaluation of the Effects of Fluids Upon the Flexural and Parallel-plate Loading Behavior of Glass Fiber Reinforced-vinyl Ester Resin Matrix Composite Pipes]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100121&lng=pt&nrm=iso&tlng=pt Commercial glass fiber reinforced-vinyl ester resin composite pipes used in onshore and offshore utilities were exposed to the action of fluids that could normally come into contact with them during their service life, namely: salt water, biodiesel and a mixture of water and oil. The influence of these fluids upon the flexural properties and parallel-plate loading behavior of the composites was evaluated. The results of the mechanical tests point out that physical aging was the main phenomenon, and that it causes a reduction of stiffness of around 20-30% – at the parallel-plate test – and a decrease of toughness of up to 40% – at the flexural test. The results of the flexural tests were very dependent of the inhomogeneous microstructure of the commercial composite analyzed. <![CDATA[Hydrophobicity Classification of Polymeric Insulators Based on Embedded Methods]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100127&lng=pt&nrm=iso&tlng=pt Hydrophobicity is an important parameter to characterize electrical properties of insulated materials. Therefore, it is an urgent task to develop on-line instruments to identify the hydrophobicity of insulated material's surface conveniently, quickly and accurately. For this purpose, a novel evaluation system with image processing and decision tree is proposed which is based on embedded platform. For obtaining satisfactory results, we first propose a mixed image segmentation method to overcome the complex conditions outside, concerning non-controlled illumination, nonstandard surfaces and unfixed shooting angle. Then we adopt four new characteristic parameters to describe the image of each sample. Finally, a classification method based on MultiBoost decision tree is conducted which synthesizes the merits of both AdaBoost and Wagging algorithm. Results indicate the procedures can be applied in the DSP (Digital Signal Processor) platform perfectly and better results can be obtained than those did in our previous study or that of some other research. <![CDATA[New Sol-gel Formulations to Increase the Barrier Effect of a Protective Coating Against the Corrosion and Wear of Galvanized Steel]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100138&lng=pt&nrm=iso&tlng=pt This study proposes a new pretreatment method that uses alkoxide precursors with a plasticizing agent; the purpose of this study is to improve the electrochemical and mechanical properties of a galvanized steel surface. Galvanized steel was covered with a hybrid film obtained from a sol that consisted of two alkoxide precursors, 3 - (trimethoxysilylpropyl) methacrylate (TMSM) and tetraethoxysilane (TEOS), with nitrate cerium in a concentration of 0.01 M and a polyethylene glycol (PEG) plasticizer. The hybrid coatings were obtained by dip-coating method with various concentrations of plasticizer (0, 20, 40 and 60 g.L-1). The hybrid films were analyzed by scanning electron microscopy (SEM), profilometry, contact angle measurements, a tribometer with the type-setting ball on the plate and electrochemical tests. The addition of the plasticizer into the hybrid films improves the corrosion resistance behavior compared to the sample without the plasticizer. The addition of 20 g.L-1 of plasticizer showed the best performance in the electrochemical tests. The mechanical behavior results indicated that higher PEG concentrations resulted in films with enhanced durability. <![CDATA[Characterization of Siloxane-poly(methyl methacrylate) Hybrid Films Obtained on a Tinplate Substrate Modified by the Addition of Organic and Inorganic Acids]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100151&lng=pt&nrm=iso&tlng=pt Tinplate is used to food packaging and other types of packages. The corrosion resistance of the tinplate has been study due the necessity of an alternative to high environmental impact of chromatization process. Therefore protective coatings as hybrid films base elaborations with different acids are studied to improve the barrier effect against corrosion. The objective of this work is characterize hybrid films deposited on a tinplate from a sol made up of the alkoxide precursors 3-(trimethoxysilylpropyl)methacrylate (TMSM), tetraethoxysilane (TEOS) and poly(methyl methacrylate) (PMMA) together with one of three acids (acetic, hydrochloric or nitric acid) and to verify their action against the corrosion of the substrate. The films were obtained by a dip-coating process and cured for 3 hours at 160 °C. The film hydrophobicity was determined by contact angle measurements, and the morphology was evaluated by SEM. FTIR measurements were performed to characterize the chemical structures of the films. The electrochemical behavior of the coatings was evaluated by techniques open circuit potential monitoring (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results demonstrate that the siloxane-PMMA films improve the protective properties of the tinplate, with the films obtained by acetic acid addition exhibiting the greatest improvement. <![CDATA[<em>In situ</em> Synchrotron X-ray Powder Diffraction Study of the Early Hydration of α-tricalcium Phosphate/tricalcium Silicate Composite Bone Cement]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100164&lng=pt&nrm=iso&tlng=pt Bioactivity, osteogenicity and mechanical properties of α-tricalcium phosphate (α-TCP) based phosphates cements can be improved by adding tricalcium silicate (C3S); however, the addition of C3S delays the precipitation and growth of calcium deficient hydroxyapatite (CDHA). Thus, the aim of this work was the study of in situ setting reaction of α-TCP/C3S composite bone cement under high energy X-ray generated by a synchrotron source within the first 72h. The results showed that the addition of C3S induces the precipitation of nanosized CDHA at early times depending on the added content. Calculated crystallite sizes showed that the higher the content of C3S, the smaller the crystal size at the beginning of the precipitation. These results are different from those obtained by conventional XRD method, suggesting that the proposed technique is a powerful tool in determining the composition and extent of reaction of CPCs surfaces in real time. <![CDATA[Effect of Pouring Temperature and Water Cooling on the Thixotropic Semi-solid Microstructure of A319 Aluminium Cast Alloy]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100170&lng=pt&nrm=iso&tlng=pt The cooling slope (CS) casting is the simplest and cheapest technique for producing feedstock materials with non-dendritic microstructure. Such materials are required for semi-solid metal (SSM) processing methods such as thixoforming. In the present investigation, the effect of the pouring temperature and the water cooling on the thixotropic microstructure of commercial A319 Al-Si cast alloy was studied. The results showed that increasing the pouring temperature slightly reduces the bulk porosity of the CS ingots. The ingots poured with water-cooling exhibited slightly lower porosity content than those poured with without water-cooling. Generally, the primary α-Al grains exhibited higher shape factor near the edge of ingot than the middle and center. Ingots poured with water-cooling exhibited lower grain size and shape factor than those poured without water-cooling. Increasing the pouring temperature increases the size α-Al grains. <![CDATA[On the Strengthening of Cement Mortar by Natural Fibers]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100177&lng=pt&nrm=iso&tlng=pt The purpose of this work is to evaluate mechanical behavior of sisal fiber reinforced cement mortar. The composite material was produced from a mixture of sand, cement and water. Sisal fibers were added to the mixture in two different lengths. Mechanical characterization of the composite and the plain mortar was carried out using three point bend, compression and impact tests. Specimens containing parallel sided notches of different root radii were loaded in three point bending in order to determine the effect of the fibers on the material fracture toughness in the presence of discontinuities. According to the results, while fiber reinforcement leads to a decrease in compressive strength, J-integral calculations at maximum load for the different notch root radii have indicated, particularly for the case of long fibers, a significant superiority of the reinforced material in comparison with the plain cement mortar, in consistence with the impact test data. <![CDATA[The Electrochemical Behavior of the NiTi Alloy in Different Simulated Body Fluids]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100184&lng=pt&nrm=iso&tlng=pt In order to improve the NiTi alloy biocompatibility, surface treatments become very important. Nevertheless, researchers use different solutions to simulate the body fluids in electrochemical assays, and the correlation between the obtained results is difficult and might not even be possible. The present paper evaluated the electrochemical behavior of polished NiTi surfaces exposed to different simulated body fluid solutions: Hanks solution, Hanks’ balanced salt (HBSS) solution, saline body fluid (SBF) solution, and Ringer solution. The electrochemical behavior of NiTi was evaluated by open circuit potential (OCP) and cyclic voltammetry tests. The surfaces of the samples were also characterized by scanning electron microscopy, which was performed after the electrochemical tests. The results demonstrated that the NiTi alloy shows the same corrosion mechanism (pitting) in all simulated body fluids that were studied. However, the corrosion potential changes for each electrolyte, being HBSS, SBF and Ringer the most corrosive solutions. Furthermore, the Hanks and HBSS solutions demonstrated good reproducibility of the electochemical results. Considering that the HBSS represents an extreme environment, this solution seems to be the most indicated to study the corrosion behavior of NiTi treated surfaces. <![CDATA[Solvent Effect on the Morphology of Lamellar Nanocomposites Based on HIPS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100191&lng=pt&nrm=iso&tlng=pt In this study, hybrid nanocomposites based on HIPS, high-impact polystyrene, were prepared in chloroform and in a 1:1 mixture of toluene and chloroform varying the quantity of organophilic montmorillonite. The morphology of the hybrid materials was investigated by X-ray diffraction (XRD) and proton relaxometry, determined in a low-field 1H nuclear magnetic resonance (NMR). The thermal characteristics were also obtained through thermogravimetric analysis. The emphasis of this study was to compare the effect of a pair of solvents against a single solvent in the formation/organization of the nanostructured materials when the solution method is applied. It was taken into consideration Interactions involving polymer-solvent, nanoparticle-solvent, and, principally, polymer-nanoparticle-solvent. The results show that the choice of solvent affects greatly the characteristic of the nanocomposites. Nanocomposites prepared with chloroform/toluene were more homogenous, more prone to exfoliate (for all organoclay concentrations), and had higher degradation temperature compared to the materials obtained with chloroform. It is clear from the data that the use of a solvent pair is important to produce good nanocomposites when using the solution method and that the clay proportion plays a role in the dispersion of organoclay in the polymer matrix. <![CDATA[Hydroxyapatite and a New Fibrin Sealant Derived from Snake Venom as Scaffold to Treatment of Cranial Defects in Rats]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100196&lng=pt&nrm=iso&tlng=pt Biomaterials are used as a promising alternative to bone grafts, including bioceramics whose composition resembles that of bone and fibrin sealants due to their hemostatic properties. The objective was to evaluate the repair of cranial defects in 40 rats, grafted with hydroxyapatite and a new fibrin sealant derived from snake venom. The animals were divided into four groups: C (control, no graft); Ha (hydroxyapatite); FS (fibrin sealant), and HaFS (hydroxyapatite and fibrin sealant). The animals were euthanized 2 and 6 weeks after surgery and wound area were submitted to analysis. After 2 weeks, immature bone was formed from the borders of the defect and in groups Ha and HaFS, few hydroxyapatite particles were surrounded by new bone. After 6 weeks, the new bone was mature and surrounded several hydroxyapatite particles, without connective tissue interposition and the volume of new bone was higher in HaFS group. The hydroxyapatite in combination with the new fibrin sealant accelerates bone repair. <![CDATA[Recovery of Steelmaking Slag and Granite Waste in the Production of Rock Wool]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100204&lng=pt&nrm=iso&tlng=pt Steelmaking slag and residues from granite cuttings are industrial wastes with considerable production, however limited applications. This work studied an inertization and recovery process of such wastes as raw materials into production of rock wool (i.e. a thermo-acoustic insulator with growing market). Several batches were produced aiming the chemical proprieties of a currently marketed rock wool. Mixtures were casted at temperatures of 1400-1500 °C, then quenched in water and also poured into a Herty Viscosimeter. Produced materials with thickness smaller than 500µm were characterized by chemical analyses, XRD, SEM, EDS and DTA. ThermoCalc software was used to simulate the cooling curves of rock wools. Results showed that incorporation of wastes does not affect the main qualities of rock wool, the thermal insulation and prevention of fire spread. Raw material batches of rock wools may assimilate up to 66% of granite waste, or 53% steelmaking slag, or 70% combining both materials. <![CDATA[Microstructure and Properties of Nickel-based C276 Alloy Coatings by PTA on AISI 316L and API 5L X70 Steel Substrates]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100212&lng=pt&nrm=iso&tlng=pt This work assessed Ni-based C276 alloy coatings by PTA with different degree of interaction with AISI 316L and API 5L X70 steel substrates. Track geometry, dilution and microstructure of coatings were evaluated by optical, scanning electron microscopy and X-ray diffraction. Properties were evaluated by hardness and wear tests. Microstructure exhibited austenite Ni-FCC dendrites and interdendrictic regions containing carbides. Dilution from 4,9 to 25,4% for coatings on API 5L X70 leaded to hardness ranging from 283 to 243 HV0,5. Otherwise, dilution between 22,3 and 41,5% for coatings on AISI 316L induced hardness from 267 to 225 HV0,5. Higher interaction with the substrate leaded to 19,8% increase of mass loss rate on API 5L X70 coatings. The slight difference for coatings properties deposited on different substrates indicated that the degree of interaction was the most significant factor. <![CDATA[Development of Electrical Conduction with Beryllium Doping of CdO Nanostructure thin Films]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100222&lng=pt&nrm=iso&tlng=pt The objective of the present investigation is to study the effect of beryllium doping on the structural, optical, and electrical properties of CdO, focusing on the improvement of carrier mobility (μ) that accompanied with high electrical conductivity and good optical transparency in the near-infrared region. Thus, nanocrystallite Be-doped CdO films were prepared by vacuum evaporation method. The characterisation of the samples was done by using X-ray diffraction (XRD), scanning electron microscope (SEM), absorption spectroscopy, and Hall measurements. The characteristic XRD patterns indicated that the prepared Be-doped CdO films were single phase of cubic CdO structure of highly [111] orientation. Scanning electron microscope analysis revealed that the studied CdO films were characterized with high-density threads (wooly structure) and the incorporation of beryllium ions modified that structure forming almost round grains. It was observed that the room temperature conductivity (σ) and mobility (μ) could be controlled through the level of beryllium doping. The utmost carrier mobility was found to be ~130 cm2/Vs in ~ 0.10% Be films maintaining a low electrical resistivity of ~ 4.14×10−4 Ω cm and a good transparency of ~ 80% in the NIR spectral region. The results demonstrate that beryllium doping in low concentration levels is a good enough dopant that might be used to improve the optoelectrical properties of CdO. Generally, the properties found can make CdO:Be films particularly interesting in application of optoelectronic devices, solar cells, and field of transparent conducting oxides (TCO). <![CDATA[Crystallization in Lead Tungsten Fluorophosphate Glasses]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100228&lng=pt&nrm=iso&tlng=pt The glass forming ability was investigated in the codoped Er3+/Yb3+ ternary system NaPO3-WO3-PbF2 with increasing amounts of PbF2. It has been found that glass samples can be obtained for PbF2 contents ranging from 0 mole% to 50 mole% for the codoped samples and an undoped sample containing 60% of lead fluoride could also be vitrified. Thermal properties of the most PbF2 concentrated glasses exhibit strong dependence of the composition with a decrease of the glass transition temperatures and thermal stabilities against devitrification with increasing the lead fluoride content. These glass samples were heat-treated near the crystallization peaks and the X-ray diffraction measurements pointed out that the dominant phase which precipitates from the glass samples containing 40% and 50% of PbF2 is the lead fluorophosphate phase Pb5F(PO4)3 whereas the sample containing 60% of PbF2 exhibits a preferential bulk crystallization of cubic lead fluoride β-PbF2. <![CDATA[Erratum]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000100233&lng=pt&nrm=iso&tlng=pt The glass forming ability was investigated in the codoped Er3+/Yb3+ ternary system NaPO3-WO3-PbF2 with increasing amounts of PbF2. It has been found that glass samples can be obtained for PbF2 contents ranging from 0 mole% to 50 mole% for the codoped samples and an undoped sample containing 60% of lead fluoride could also be vitrified. Thermal properties of the most PbF2 concentrated glasses exhibit strong dependence of the composition with a decrease of the glass transition temperatures and thermal stabilities against devitrification with increasing the lead fluoride content. These glass samples were heat-treated near the crystallization peaks and the X-ray diffraction measurements pointed out that the dominant phase which precipitates from the glass samples containing 40% and 50% of PbF2 is the lead fluorophosphate phase Pb5F(PO4)3 whereas the sample containing 60% of PbF2 exhibits a preferential bulk crystallization of cubic lead fluoride β-PbF2.