bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Electron Backscatter Diffraction to Shape Memory Alloys
Authors: Bassani Paola
Published: August 2012

This overview highlights very recent application of electron backscatter diffraction (EBSD) to shape memory alloys, as main investigation technique but also as ancillary technique for other characterization methods. Over the last two decades EBSD in the scanning electron microscope has become a powerful tool for the characterization of many materials and transformation. In the mean time, shape memory alloys (SMA) are continuously studied: from a theoretical point of view, in order to clarify unsolved fundamentals of their phase transformations and characterize or develop new SMA systems, and from an engineering point of view, to solve design and processing problems related to the continuously growing examples of applications. Application of EBSD to SMA, even if hindered by limitations generally found also in other metallic system when phase transformation and martensitic phases are involved, provided useful information for both research areas.
Nonstationary Theory of the Thermal Explosion for Monomolecular Exothermic Reactions
Authors: Filimonov Valeriy
Published: August 2012

A new approach to the consideration of the thermal explosion macrokinetic features for monomolecular reactions in homogeneous systems based on a strict accounting of burnout during the reaction process is proposed. It is established, that the qualitative changes of the phase trajectory structure (phase portrait) on the plane: heating rate-temperature determine the characteristic modes of reaction. This approach makes it possible to go beyond the Semenov theory and allows us to consider the variety of the reaction modes. From this point of view, the theory of Semenov is a special case which is valid only for reactions of zero order. The phase trajectories analyze on the parametrical plane Semenov criterion – Todes criterion gives an opportunity to define the regions of the thermal explosion degeneration, the transition regions and the region of the thermal explosion realization. With the use of such consideration, the necessary and sufficient conditions of the thermal explosion are found.
Fabrication of 3D Hierarchical Scaffolds by a Hybrid Process Combining Low-Temperature Deposition and Electrospinning
Authors: Yu Yong Ze , Han Zhen Zhong , Liu Ying , Fang Shu Hui , Liu Yuan Yuan , Hu Qing Xi
Published: August 2012

An ideal scaffold should mimic the morphology of the natural extracellular matrix and have good mechanical properties and biologically functional. So, the key point of fabricating of scaffolds is to realize the composition of scaffolds by materials having different physical and biological properties and control porous structure accurately. In this study, we propose a novel technology combining a low-temperature deposition, electrospinning process and freeze-drying to produce a hierarchical 3D biomedical scaffold consisting of micro-sized highly porous chitosan-gelatin strands and nanosized PCL fibers network. Scanning electron microscopy analysis showed that the scaffold composed of parallel aligned micro-strands in a grid-like arrangement layer by layer, along the thickness direction intercalated by a network with randomly distributed nanofibers. The stand of macro-scaffold composed of natural-derived biomaterials and nanofibers composed of synthetic biomaterials were bonded together firmly to form a stable network structure.
Ultrasonic Vibration Characteristics of Nano-Composite Ceramic in the Ultrasonic Polishing Process
Authors: Zhang Ming , Jiao Feng
Published: August 2012

The ultrasonic polishing test of the nanoZrO2-Al2O3composite ceramics is done under the two-dimensional ultrasonic polishing device, which is developed by us. In this process, the ultrasonic amplitude-frequency characteristic testing is done by the DASP software. There are certain amplitudes at some frequency points, which can be seen from the spectrum and the three-dimensional spectral array maps, but only one the largest amplitude appears. This shows the resonance points appear when the ultrasonic is passed to the nanocomposite ceramic plate after it is amplified by the horn. This phenomenon is analyzed by the second-order surface wave theory and the waves are surface waves, which are generated by surface waves. These explain the good polishing surface quality and high efficiency under the two-dimensional ultrasonic polishing in the same conditions.
Microstructures and Properties of Ti Matrix Composite Coatings with Ex/In Situ TiC Reinforced
Authors: Yu Qing , Sun Yao Ning , Sun Wen Lei , Zhang Xu Dong
Published: August 2012

Using laser cladding technique, TiC reinforced Ti matrix composite coatings were fabricated by preplacing TiC, (Ti+C), (Ti+TiC) powders respectively on the TA2 pure titanium surface.By means of XRD, SEM and Hv-Test, microstructures and microhardness were investigated. The results show that phases of the coatings are all composed of TiC and α-Ti. Delamination phenomenon appears when laser clad pure TiC coating, which has deleterious effect on properties. TiC phase is in-situ synthesized during laser clad (Ti+C) coating, but microstructure is coarse. Microstructure of (Ti+TiC) coating is the most uniform and dense of the three coatings. The microhardness sequence of the three coatings is (Ti+TiC)>TiC>(Ti+C), and the maximum value is Hv1246, Hv1213 and Hv1135 respectively. The main reason leads to the highest micro-hardness of (Ti+TiC) coating is the Ti powder is beneficial to laser cladding and large amount of TiC reinforcement formed which is compact and uniform.
Researching a Online Method of Measuring Three-Dimensional Deformation for Large Overhead Crossbeam
Authors: Han Wei , Wu Li Ming , Deng Yao Hua , Zhang He Yun
Published: August 2012

Aiming at the difficulty of online measurement for three-dimensional deformation of large overhead crossbeam in gantry CNC machining centre, this paper proposes a measuring method based on multi-points attitude of crossbeam-body. Real-time measuring the attitudes of some equidistant points on crossbeam-body, dealing with the measurement information by adopt shockproof filtering, wavelet denoising and smoothing. Then infer the formulas to calculate deformation of each point along different directions ofx-axis,y-axis,z-axis. The experiment uses triaxial acceleration sensor modules to measure crossbeam attitude. Experimental results show that the minimum deformational angle can be measured low to 0.06°. And if the spacing between sensor modules has mm level accuracy, the precision of calculation about deformation can reach up to 10-3mm level. In addition, this method is strongly suitable for on-site environment, and it can lay a foundation for further researching about prediction and compensation in the CNC processing.
Structural Dynamic Analysis for the Natural Frequency of the Horn and Workpiece Combination
Authors: Cheng Xue Li , Si Yao Hua , Li Xin Sheng
Published: August 2012

In order to find the vibration frequency when the workpiece obtains optimum vibration effect, the structural dynamic analysis were conducted in this paper, using finite element dynamic analysis methods on the horn and the workpiece combination. Through the vibration mode analysis, the resonant frequency of the horn and workpiece combination along the workpiece axial direction (y) is 20.845KHZ, along the x, z direction are respectively 22.373KHZ and 22.375KHZ, which are in the range of the ultrasonic generator frequency adjustment. Through the harmonic response analysis, the displacement amplitude in the big end of the horn is substantially equal, the displacement of each node on the symmetry axis of the horn increases firstly and then decreases along the axial, reaching the minimum at the wave node, and then gradually increases, reaching the maximum on the free end. The magnification is up to 18.84um, which can meet the requirements of ultrasonic vibration. In addition, it can be seen from the model graph of the workpiece thin segment that in the ultrasonic loading conditions, the thin segment of the workpiece at the middle position are mostly easy to break, which is consistent with the theoretical analysis. These findings and follow-up of test results are consistent, which proved the validity and reliability of software analysis.
Research on the Primary Parameter of Track Circuit Test
Authors: Zou Xiang , Zhu Xi Lin , Yu Yong , Huang Chen Jun
Published: August 2012

The primary parameter of the track circuit is often the test data in the maintenance of the signal, is the important basis for designing equipment of track circuit and is the basic parameter of track circuit parameter, primary parameter of track circuit can be used for rail simulation experiment of track circuit parameters, analysis of rail leakage and calculation of track circuit. This paper studies the primary parameter of track circuit test method, the result can be used for calculation track circuit parameter.In the practical application, primary parameter of track circuit test can have positive significance in the division of track circuit district and the adjustment of working state.
Structural Optimization of a Spacecraft Catheter Connector
Authors: Wang Hui Feng , Wang Guang Lin , Shao Dong Xiang , Liu Hai Tao , Lu Ze Sheng
Published: August 2012

Setting up the FEM model of a spacecraft catheter connector, analysis its static strength and optimized its structure, Shorten the diameter and reduced the weight of catheter connector, within the requirement of properties.
Design and Experimental Analysis of an Animal Traumatic Brain Injury Test Platform
Authors: Wang Bing , Tursun Mamatjan , Long Jun , Liu Shao Ming , Ding Feng Rui
Published: August 2012

In this research, a simulation model of an animal Traumatic Brain Injury test platform is established using Solid Edge software. Applying the Biological Functions testing system and Matlab, performance analysis for the test platform was undertaken.
Automatic Inspection System of Small Plastic Gears Based on Machine Vision
Authors: Chen Jian Zhe , Wang Gui Tang , Chen Jian Qiang , Yin Xin Liang
Published: August 2012

Small plastic gear is generally made by injection molding.But the injection molding process and mold have problems with missing tooth, shrink, more material, less material and inaccurate roundness and so on. Furthermore, using manual inspection will appear phenomenon of low efficiency, false detection and leak detection. To solve these problems, this paper introduces an automatic inspection system of small plastic gears based on machine vision. The system consists of feeding and sorting machine control system and machine vision inspection system of the gear defects. Mechanical control use digital servo control technology to achieve automatic nesting, feeding, positioning of gear workpiece, and depend on the inspection result of machine vision system to sort. After acquired gear image through a camera, Machine vision system uses median filtering, binarization, edge detection algorithms to process image. Then the system adopts template matching algorithm to obtain the inspection result and send the result to the sorting controller, which achieve automatic smart inspection of gear. The automatic inspection system has accurate, efficient, intelligent and other advantages.
Design of Remote Monitoring System of Robot Based on FPGA
Authors: Zhang Cheng Guang , Wang Yi
Published: August 2012

In the current monitoring system, for the monitoring sites (such as storage, home, radioactive places and other harmful places), no dead ends and comprehensive monitoring is completed by installing a large number of fixed cameras and hiring many security persons to achieve, a lot of cameras installed are complicated; expensive and wasting a lot of manpower and material resources. Meanwhile, the fixed camera monitoring is just rigid; no early warning functions and requiring the security persons to be on duty all the time. At the same time, the records of on-site monitoring need to be large capacity storage medium. Therefore, to solve the problems of above in practical, we design an intelligent network monitoring system which is a set of non-dead mobile monitoring; automatic warning; automatic voice alerting; automatic storage of suspicious scene. By fixing the cameras; wireless routers; GPRS module; voice module and power management modules, with the Altera DE2 board to build a wheeled robot. The wheeled robot realizes the real-time monitoring of unmanned sites and solves the issues of complex installing and adverse monitoring to a large extent.
Numerical Simulation of Transmission Laser-Welding Melting Depth on Thermoplastic
Authors: Wang Zhen , Wang Yun Shan , Lei Jian Bo
Published: August 2012

The principle of laser welding of combined translucent thermoplastic and absorbance thermoplastics is that laser transmit through translucent material and shoot at laser absorptive material, where the material absorb energy and melt down to complete welding. This paper studied the applicability of basic law of laser transmission welding beam mechanism and light absorption process – Beer-Lamber Law to plastic materials. Numerical simulation model of melting depth was established. Single factor relevance curve and double factor relevance surface were drawn with MATLAB; Impact of laser power, distance between weld zone and lens and scanning speed to melting depth was quantitatively analyzed on melting depth, which provided effective reference for setting parameters in the experiment.
Safety Recession Characteristics of High Speed Milling Cutter
Authors: Jiang Bin , Zhao Pei Yi , Xia Dan Hua , Song Ji Guang , Wang Song Tao
Published: August 2012

In order to research the influence property of pre-tightening force, centrifugal force and dynamic cutting force on cutter components, and reveal safety recession of the cutter components, this paper makes load analysis for high speed milling cutter, studies cutter deformation, joint surface crushing, ductile fracture and other damage characteristics, gets the safety recession order of cutter components by safety margin theory. By means of the grey correlation analysis for safety recession, acquires the safety recession model of cutter. The experiment results confirmed that screw component firstly occurs the safety recession, and the safety recession model has certain reliability.
Network Characteristics Analysis of the Xinjiang Regional Logistic Based on Complex Networks
Authors: Liu Rui Yan , Yuan Yi Ping , Tian Shu Guang , Li Xiao Juan
Published: August 2012

Reasonable logistics system plays a fundamental role in the process of regional economic development. With the development of Xinjiang's energy resources conversion strategy is ceaseless and thorough, as the country imported energy and scarce mineral resources international channel, Xinjiang internal and external logistics hub action are highlighted with each passing day. In this paper the complex network theory is applied to the Xinjiang regional logistics network, important cities, ports, warehousing point for a node to connect these nodes highway straight-line distance of the railway side, constructed the Xinjiang regional characteristics of the logistics network model. Select the node degree distribution, betweenness, average path length, clustering coefficient as a measure, static statistical properties of the network are analyzed. Provide basic data for the Xinjiang regional logistics network.
Virtual Assembly and Kinematic Simulation of Gear Form Grinding Machine Based on Pro/E
Authors: Ren Xiao Zhong , Xie Feng Kun
Published: August 2012

On the basis of establishing 3D modeling of gear form grinding machine, all levels of subassemblies of the grinding machine were assembled. Then the virtual assembly of total grinding machine was completed. Based on the kinematic simulation module of Pro/EMechanism, and combined with the virtual machine assembly model, the simulation analysis on machine movement was carried out. By simulating the actual working situation of the model, it could be checked whether the location, movement and load of the product could meet actual requirements before manufacturing the physical prototype of the product. This method is helpful for improving one-time success rate of new product development and saving product development cost.
A Decision Tree Method Based on Support Vector Machineto Identify Egg Embryo
Authors: Xie Tan Cheng , Mao Heng Xuan , Xu Yan Wei , Nang Xiang , Hu Xiao Jing
Published: August 2012

This paper mainly studies a decision tree method based on support vector machine to identify egg embryo. It analyses the main characteristics of the types of egg embryo and sets up a kind of multilayer decision tree classifier by using "solution space". And it figures out the correct rate of the decision tree classifier, which concentrates on the types of egg embryo. By introducing the support vector machine (SVM) algorithm based on the structure of the binary tree for multi-class classification, it identifies different kinds of egg embryo. Not only does this method make the decision capability of the optimal one in every level of the decision tree, but also assures the overall optimal performance of the whole decision tree, and effectively improves the correct recognition rate of the decision tree classifier about the types of egg embryo.
Research on RFID-Based Production Data Aggregation Technology
Authors: Hu Rong Song , Liu Li Lan , Yu Tao
Published: August 2012

Because of the advantage of RFID, people have attached importance to this technology. The RFID application system needs a convenient and efficient way to transmit data on Internet. The proposed method is data transfer with J2EE. It can provide a great solution to remote communicate with RFID systems, and make the RFID application system operating more efficient. The system has been successfully applied to Shanghai Key Laboratory of Mechanical Automation and Robotics, and satisfactory results are obtained.
Well-Posedness of the Gnedenko System with Multiple Vacations
Authors: Yunus Bilikiz , Haji Abdukerim
Published: August 2012

We investigate the solution of the Gnedenko system with multiple vacation of a repairman. By using-semigroup theory of linear operators, we prove well-posedness and the existence of the unique positive dynamic solution of the system.
Experimental Verification of the Analytical Method for Estimated S-N Curve in Limited Fatigue Life
Authors: Strzelecki Przemysław , Sempruch Janusz
Published: August 2012

The paper presents method for determined S-N curve used only static properties of material. To verified this algorithm, material C45+C was tested to provide reference fatigue characteristics. Tests was carrying out with rotating bending by equipment own design. Test machine was checked for correct working according standard ISO 1143. Verification of analytical method has been realized by statistical calculation assume null hypothesis that coefficient of slope of straight line and absolute term estimated by proposed algorithm is equal to coefficient of slope and absolute term estimated from experimental data. Calculated value of statistics has shown that there is no reason to reject null hypothesis for proposed method.
Wollastonite as a Flux for Ceramics Bodies
Authors: Bragança S.R. , Lengler H.C.M , Bergmann Carlos Pérez
Published: August 2012

Wollastonite is a calcium silicate mineral natural or synthetic. Commercial wollastonite starts to melt at about 1450°C and can not be considered a "flux" as alkali feldspar. For this function, it depends on the reaction with other raw materials. Faced with this, came the goal of this work which was to investigate the mechanism of action of wollastonite as a ceramic flux. The use of wollastonite in ceramic bodies was investigated by analysis of its reactivity with other materials such as quartz, kaolin, talc and feldspar. It was analyzed the technological properties of the final parts, especially in relation to the firing temperature, phase formation and technological properties (mechanical strength, porosity, etc.). The results of this characterization showed that the technical properties of the parts are developed according to commercial porcelain products.
Sintering Behavior of LZS Glass-Ceramics
Authors: Teixeira Jaime Domingos , de Oliveira Antonio Pedro Novaes , Boehs Lourival , Cesconeto Francielly Roussenq , Siligardi Cristina , Pereira Manuel Alfredo
Published: August 2012

Sintering and crystallization behaviors of a LZS glass-powder were investigated by means of thermal shrinkage, differential thermal analysis, X-ray diffraction as well as density and mechanical properties measurements. The melted glass, 9.56Li2O.22.36ZrO2.68.08SiO2(wt%) first was cast into water to provide a frit for milling. The milled glass powder (mean particle size 5.0 µm) was then uniaxially pressed at 100 MPa and the obtained samples were isothermally sintered in the 800-950°C temperature range in air for appropriated time intervals (15-120 min). Sintering was found to start at about 640°C and crystallization took place just after completion of sintering and was almost complete at 920°C. The glass powder compacts crystallized into lithium and zircon silicates so that glass-ceramics with relative densities between 84 and 99% were obtained reaching maximum hardness and bending strength values of 8 ± 0.5 GPa and 214 ± 20 MPa, respectively.
Influence of Cu and Ti Doping on Hard Metal Matrix of Diamond Embedded Composites for Drilling Tools
Authors: Skury Ana Lúcia Diegues , Bobrovinitchii Guerold Sergueevitch , de Azevedo Marcia G. , Monteiro Sérgio Neves
Published: August 2012

The lifetime of drilling tools for petroleum well perforation is strongly affected by the type of insert at the crown of the tool. Usually, this insert is made a of hardmetal (WC-Co) cermet with embedded diamond particles. In the present work an investigation on the effect of Cu and Ti as doping agents on a WC-6%Co cermet was conducted. I was found a change in coercive force in the interval 12 to 34 kJ/m and harness from 73 to 89 HRA with improving adhesion. It was also shown that this could significantly increase the operational capacity of a drilling tool.
Synthesis and Characterization of SrO-Supported Al2O3 Applied as Heterogeneous Catalys
Authors: Pereira Gilberto J. , Ortega Fernando dos Santos
Published: August 2012

In this work, samples of 15 mol% Sr-doped Al2O3 were synthesized by Pechini's method and calcined at 900°C. DRX analysis showed that only corundum phase is present, and no shift on the main peaks was observed, suggesting that the additive is preferentially located on the surface of nanoparticles as a surface excess. SrO show high basic character and is applied as heterogeneous catalyst in transesterification of soybean oil to produce biodiesel. Since SrO is difficult to obtain through Pechinis method, due to high stability of SrCO3, the use of Al2O3 as a catalyst support produced via polymeric precursor was studied, and the reaction of transesterification was successfully made, because the crystallization of strontium carbonate on the corundum surface was avoided using the washing procedure. Also, the catalyst was characterized by DSC, isoelectric point and surface area.
Dispersed Hydroxyapatite Bioglass 45S5 Composites: Comparative Evaluation of the Use of Bovine Bone and Synthetic Hydroxyapatite
Authors: da Silva Antônio Carlos , Aparecida A.H. , Braga F.J.C.
Published: August 2012

The bovine bone and sintetic hydroxyapatite (HA) bioceramics are reference materials to employment as a bone substitute, however, their slow rate of degradation and its low rate of bioactivity index (Ib) are presented as limiting factors for application as bone graft. In contrast, the bioglass is a resorbable and osteoinductive material. the present work objective the development of composites of dispersed bovine bone or sintetic HA in silicate-phosphate bioglass, seeking to obtain a biomaterial with properties suitable for application as bone grafts. The composites were prepared by mixing between the powder components followed by sintering for 1h. Were used HA and bioglass (45S5) with particle size <240μm. The tested proportions of HA/45S5 were 20/80, 30/70 and 40/60 (wt%). The composites characterization was made employing scanning electron microscopy, Infra-Red Spectrometry and hydrolytic resistance test. The test results indicate the potential use of the materials developed for applications such as bone graft.
Synthesis of Alpha-Tricalcium Phosphate by Wet Reaction and Evaluation of Mechanical Properties
Authors: Thürmer Mônica Beatriz , Vieira Rafaela Silveira , Fernandes Juliana Machado , Coelho Wilbur Trajano Guerin , Santos Luis Alberto
Published: August 2012

Calcium phosphate cements have bioactivity and osteoconductivity and can be molded and replace portions of bone tissue. The aim of this work was to study the obtainment of α-tricalcium phosphate, the main phase of calcium phosphate cement, by wet reaction from calcium nitrate and phosphoric acid. There are no reports about α-tricalcium phosphate obtained by this method. Two routes of chemical precipitation were evaluated and the use of two calcinations temperatures to obtain the phase of cement. The influence of calcination temperature on the mechanical properties of cement was evaluated. Cement samples were characterized by particle size analysis, X-ray diffraction, mechanical strength and scanning electron microscopy. The results demonstrate the strong influence of synthesis route on the crystalline phases of cement and the influence of concentration of reactants on the product of the reaction, as well as, on the mechanical properties of cement.
Influence of Organic Solvent on Solvothermal Synthesis of Samaria and Gadolinia Doped Ceria – Nickel Oxide Composites
Authors: Arakaki Alexander Rodrigo , Cunha Sandra Maria , Yoshito Walter Kenji , Ussui Valter , Lazar Dolores Ribeiro Ricci
Published: August 2012

The synthesis and ceramic processing of samaria and gadolinia doped ceria - nickel oxide composites, mainly applied as Solid Oxide Fuel Cell anodes, were studied in this work. Powders with composition Ce0.8(SmGd)0.2O1,9/NiO and mass ratio of 40/60%, were synthesized by hydroxide coprecipitation with CTAB surfactant, followed by solvothermal treatment in n-butanol, ethanol and n-propanol at 150 °C for 16 hours, calcination at 600°C for 1 hour and milling. Sintering of compacted samples was performed at 1300°C for 1 hour. The powders were analyzed by X-ray diffraction, scanning electron microscopy, nitrogen adsorption method (BET), laser beam scattering (Cilas) and TG/DTA. The ceramics were analyzed by scanning electron microscopy, EDS, XRD and density measurements by Archimedes method. The results showed that the powders have a high specific surface area (42 - 85 m2/g). The ceramic characterizations showed a high chemical homogeneity and density value of 99% TD for powders treated with ethanol and propanol.
Coating Mortar Using Rice Husk Ash as Binding
Authors: Bezerra Izabelle Marie Trindade , Figueiredo Suélen Silva , de Carvalho João Batista Queiroz , Neves Gelmires Araújo , de Souza Jozilene , Menezes Romualdo Rodrigues
Published: August 2012

The use of agricultural waste has become a necessity due to the high environmental cost derived from its improper disposal in nature. In this scenario, rice husks, as well as the ash produced by burning, became worrying in certain regions of the country due to the large volume produced annually [.
Use of Waste Flat Glass in the Formulation of Masses for White Porcelain in Partial Replacement of Feldspar
Authors: de Sousa Porto Valdênia , Cavalcanti Maria do Socorro L. , Cruz Tatiana Borba , da Silva Morais Crislene R. , de Lima Santana Lisiane N.
Published: August 2012

In the production of white ceramic, the feldspar is used as flux that provides the manufacturing of products more dense and with low porosity. Although this is a raw material of great importance for white ceramic, the feldspar is a natural resource, therefore, non-renewable and your uncontrolled extraction can cause environmental problems. In this perspective, several scientific research is being carried out looking for alternatives to replace this product by other substances. The use of waste glass in partial replacement of feldspar in the production of ceramic body is extensively researched, because these materials present flux properties and reduces environmental impacts. Therefore, the purpose of this study is to verify the possibility of partial replacement of feldspar by waste flat glass in the formulation of the masses for white porcelain. For the research, feldspar and waste glass were characterized by the following techniques: chemical analysis, DTA, TG and infrared for possible comparison of the properties of these materials. The results demonstrated the possibility of utilization of waste flat glass in the formulation of ceramic bodies, since they have similar characteristics.
Systematic Characterization of Different Quaternary Ammonium Salts to be Used in Organoclays
Authors: Barbosa Renata , Souza Dayanne Diniz , Araújo Edcleide Maria , de Mélo Tomás Jefférson Alves
Published: August 2012

Studies of degradation have verified that the decomposition of some quaternary ammonium salts can begin to be significant at the temperature of about 180 ° C and like most thermoplastics are processed at least around this temperature, the thermal stability of the salt in clay should always be considered. Some salts are more stable than others, being necessary to study the degradation mechanisms of each case. In this work, four quaternary ammonium salts were characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). The results of DSC and TG showed that the salts based chloride (Cl-) anion begin to degrade at similar temperatures, while the salt based bromide (Br-) anion degrades at higher temperature. Subsequently, a quaternary ammonium salt was chosen to be used in organoclays, depending on its chemical structure and its thermal behavior.
Evaluation of the Permeation of O2, Co2 and Water Vapor in Membranes of Polyetherimide/Clay National Nanocomposites
Authors: Medeiros Vanessa Nóbrega , Leite Amanda Melissa Damião , da Paz Renê Anísio , Araujo Edcleide Maria , Pessan Luiz Antônio
Published: August 2012

The membrane separation process, although is recently, is increasing in applications such as purification, fractioning and concentration of substances in several industries. The membranes to gas separation present specific advantages when compared with conventional separation process (such as, cryogenic distillation and adsorption). Composite membrane has been widely applied in gas separation. The interest in the nanotechnology development in the last decade allows the increase in the nanocomposite area due to the special properties presented by these materials. In the nanocomposite the nanometric particles are dispersed in the polymer matrix. The polymer matrix used in this work was a polyetherimide (PEI), which is the most popular polymers for the preparation of membrane due to its solvent resistance and high selectivity. These membranes were obtained from polyetherimide (PEI) with bentonite clay from Paraiba/Brazil, by solvent evaporation method, and applied to gas permeability. The membranes were characterized by permeability to O2, CO2and water vapor. The results present in this study show good expectation.
Elaboration and Characterization of Siloxane-PMMA Hybrid Films on Tinplate Substrates
Authors: Kunst Sandra Raquel , dos Santos Rogério Freitas , Vieira Deisi , Oliveira Cláudia Trindade , Sarmento Victor Hugo Vitorino , Malfatti Célia de Fraga
Published: August 2012

The characteristics of siloxane-PMMA hybrid films permit the obtaining of coatings with thickness of few microns without cracking. Besides, the methacrylate groups (MMA) can be easily polymerizated by UV irradiation or thermal treatments. These hybrids can also be applied in anti-corrosive coatings for metals and alloys, replacing chromates which exhibit high toxicity. In this context, the aim of this work is to study the behavior of tinplate coated with a siloxane-PMMA hybrid film by dip-coating process and cured by thermal cure process. The systems were characterized by electrochemical, morphological and physicochemical analysis. Preliminary results showed that the systems studied presented a regular and adherent siloxane-PMMA hybrid film, which increased the corrosion resistance of tinplate substrates.
Diffusion Coefficients of Interest for the Simulation of Heat Treatment in Rare-Earth Transition Metal Magnets
Authors: de Campos Marcos Flavio
Published: August 2012

In the case of the modeling of sintering and heat treatments, the diffusion coefficients are an essential input. However, experimental data in the literature about diffusion coefficients for rare-earth transition metal intermetallics is scarce. In this study, the available data concerning diffusion coefficients relevant for rare-earth transition metal magnets are reviewed and commented. Some empirical rules are discussed, for example the activation energy is affected by the size of the diffusing impurity atom. Diffusion coefficients for Dy, Nd and Fe into Nd2Fe14B are given according an Arrhenius equation D=D0exp (-Q/RT). For Dy diffusion into Nd2Fe14B, Q 315 kJ/mol and D08 . 10-4m2/s.
Analysis of the Behavior of a Metallic Filter in Particle Removal under High Pressure Conditions
Authors: Tanabe Eduardo Hiromitsu , Innocentini Murilo Daniel de Mello , de Barros Priscila Martins , Aguiar Mônica Lopes , Coury José Renato
Published: August 2012

This study aimed to examine the behavior of different filter media used in gas filtration at high pressure. Trials were carried out having phosphate concentrate as the particulate matter and compressed air as fluid. Operating conditions were evaluated at the following absolute pressures of the system: 193, 393 and 693 kPa, and the gas velocity was kept constant at 0.05 m/s. The results indicated that, for a given pressure drop at the filter, the highest absolute pressure applied to the system (693 kPa) yielded the highest powder mass deposited on the filter medium. An analysis of the porosity of dust cakes revealed that the increase in pressure resulted in cakes which were more porous and less resistant to gas flow. It was also verified that the increase in the pressure of the system provided an increase in the fractional efficiency of the filters for particles smaller than 5 μm.
Modeling the Transport Phenomena of TiO2 Nanoparticles into Leachate of Municipal Waste Landfills
Authors: de Castro José Adilson , Pereira B.A. , Tassi Eliana , Pini R. , Araujo A.S.F. , Valadão I.C.P.
Published: August 2012

Several nanomaterials have been currently developed and new applications has became possible due to the special materials performance requirements. The TiO2nanoparticles are of special interest due to the wide range of applications from cosmetics to paint and new applications have continuously been searched. However, the effect of these particles into the environment need detailed investigation since some deleterious effects on the ecosystems have been observed. This paper deals with the mechanism of nanoparticles absorption/desorption by soil landfills. A long term simulation of the nanoparticles motion and contamination plume is carried out in the Volta Redonda Municipal Waste landfill and main transport parameters are determined. The model is used to predict the concentration of TiO2nanoparticles in suspension on the leachate of Municipal Waste landfills and the rate of particles dynamically attached into the soil particles
Evaluation of Constitutive Equation for Stress in Solids in Porous Media Composed of Bridging Agents Used in Drilling Fluids
Authors: Moreira Bruno Arantes , Silva Flávia Cristina Assis , dos Santos Sousa Larissa , Arouca Fábio de Oliveira , Damasceno João Jorge Ribeiro
Published: August 2012

During oil well drilling processes in reservoir-rocks, the drilling fluid invades the formation, forming a layer of particles called filter cake. The formation of a thin filter cake and low permeability helps to control the drilling operation, ensuring the stability of the well and reducing the fluid loss of the liquid phase in the interior of the rocks. The empirical determination of the constitutive equation for the stress in solids is essential to evaluate the filtration and filter cake formation in drilling operations, enabling the operation simulation. In this context, this study aims to evaluate the relationship between the porosity and stress in solids of porous media composed of bridging agents used in drilling fluids. The concentration distribution in sediments was determined using a non-destructive technique based on the measure of attenuated gamma rays. The procedure employed in this study avoids the use of compression-permeability cell for the sediment characterization.
Characterization and Efficiency of ZnAl2O4 Spinel Synthesized by Combustion Reaction on the Esterification and Transesterification of Soybean Oil
Authors: Feitosa Alex Cavalcanti , Leal Elvia , Barbosa D.C. , Meneghetti Simoni Margareti Plentz , Kiminami Ruth Herta Goldsmith Aliaga , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

This paper proposes to assess the efficiency of ZnAl2O4obtained by combustion reaction on the process of esterification and transesterification of soybean oil to biodiesel production. In the synthesis it was used three heating conditions: spiral resistance, muffle furnace, and microwave oven. In order to investigate the influence of the heating source on the structure, morphology, and on the catalytic activity, the samples were characterized by XRD, FTIR, granulometric analysis, TGA, carbon content, TEM, and gas chromatography. The results showed that it was possible to obtain the ZnAl2O4cubic phase with traces of ZnO. The ZnAl2O4monophasic was just obtained by the synthesis carried out in the microwave oven and in the electrical resistance. All the samples showed a typical morphology of dense agglomerates and low carbon content. The samples also presented low catalytic activity in the esterification and transesterification process under the adopted conditions.
Investigation of Material Combinations Processed via Two-Component Metal Injection Moulding (2C-MIM)
Authors: Dutra Gabriel Benedet , Mulser Marco , Calixto Roger , Petzoldt Frank
Published: August 2012

Joining materials with different properties into a single component is an attractive solution that allows producing parts with unique properties. In this respect, Two-Component Metal Injection Moulding (2C-MIM) presents numerous advantages, since the moulding and joining stage are performed in a single process step. In this work, the challenges, which occur when different materials are combined, are elucidated. Furthermore, the contact between metals with unequal chemical compositions leads to atomic interdiffusion that forms an interface layer. The interface quality is crucial to the production of intact parts after processing. Different material combinations are co-sintered and the interfaces are characterized by means of optical microscopy and EDX/SEM line scans. Further, thermodynamic and kinetic simulations are used to examine the interdiffusion in detail. The results show promising possibilities to combine different materials and helpful methods to examine the interface.
Preparation of Metal Matrix Aluminum Alloys Composites Reinforced by Silicon Nitride and Aluminum Nitride through Powder Metallurgy Techniques
Authors: de Araujo Everthon Rodrigues , de Souza Marcio Marcelo Sampaio , Filho Francisco Ambrozio , Gonzalez Cezar Henrique , de Araújo Filho Oscar Olimpio
Published: August 2012

The aliminium alloys are of particular interest to both the aerospace industry and automotive industry because of their attractive combinations of properties such as medium strength, formability, weldability, corrosion resistance and low cost. Compared with a metal matrix material, significant improvements in the mechanical and physical properties such as strength, toughness, and thermal conductivity can be achievied in metal matrix composites (MMCs). In this work of investigation aluminium alloy AA6061 was reinforced by 5, 10 and 15% (in mass %) of Si3N4 (silicon nitride) and AlN (aluminium nitride) by mechanical alloying in a vibratory type SPEX mill, cold uniaxial compaction and vacuum sitering in order to investigate the influence of the particulate phase in the microstructure and mechanical properties of the composites obtained. The microstructure of the powders and the sintered materials were evaluated by means of SEM and the hardness and were evaluated by hardness test.
Obtention and Characaterization of the Sn-Ni-Fe-Cu Alloys Applied in Diamond Saw Blade Production
Authors: Skury Ana Lúcia Diegues , Bobrovinitchii Guerold Sergueevitch , de Azevedo Marcia G. , Monteiro Sérgio Neves
Published: August 2012

In the production of metallic saw blades segments impregnated with diamond particles, there are two basic functions of the metal-based matrix. First, to hold tightly the particles and, second, to display wear rate compatible with the diamond loss. The most common matrix materials are composed of either cobalt or iron, nickel, copper, bronze alloys and tungsten alloys. This paper investigated the microstructure and mechanical properties of Ni-Fe-Cu-Sn alloys as the metallic matrix of saw blade segments. It was found that the Ni content significantly influences the microstructure and mechanical properties of the alloy. Information on the diamond bonding efficiency of the Ni-Fe-Cu-Sn alloy as a cutting tool matrix were disclosed.
Mechanical and Structural Characterization of Cu-Ni-Ag/Y2O3 Composites Obtained by Powder Metallurgy
Authors: Okazaki Anderson Kenji , Martins Marcos Vinícios Surmani , Carvalhal Marcelo , Monteiro Waldemar Alfredo , Carrió Juan Alfredo Guevara
Published: August 2012

Metal-ceramic composites are recently being used as electrode materials in solid oxide fuel cell (SOFC), which have received much attention as alternative energy sources. In this work cermets of Cu-Ni-Ag/Y2O3 were synthesized with different quantities of Ni and Ag. Various samples were prepared from pure precursors by conventional powder metallurgy processing and sintered at 800°C. The characterization by differential scanning calorimetry (DSC) and thermal gravimetric analyze (TGA) indicate that the presence of Y2O3 could increase the corrosion resistance of the metallic copper alloys. The copper crystalline structure presents internal strengths and possibly crystallites with different cell parameters due to the effect of thermal and mechanical treatments in presence of Y2O3. The highest electrical conductivity and highest hardness were obtained for the composition with 5% Y2O3 and 5% nickel, which increases the hardness and could contribute to the higher conductivity through a precipitation mechanism.
Service Life Extension of Stainless Steel Wire Mesh Belts for Sintering Furnaces
Authors: Wehr-Aukland Anna , Bowe Donald J. , Zaffuto Anthony M. , Gabler Jeremy , Silva Gian Ricardo C.
Published: August 2012

The service life of stainless steel wire mesh belts in sintering furnaces is limited, because material deterioration results in wire fracture. A newly developed humidification system establishes a furnace atmosphere that maintains a protective oxide scale on the belt surface throughout the sintering process and at the same time creates an environment that is reducing to the sintered metal compact. This work includes thermodynamic calculations of the furnace atmosphere dew points that satisfy these oxidation / reduction criteria. Scanning Electron Microscopy, combined with Energy-dispersive X-ray Analysis, and mechanical testing methods have been used to compare belts that have undergone the same length of service in a nitrogen-hydrogen atmosphere and in an atmosphere that was modified using the newly developed humidification method. The material examinations have revealed that the new humidification system significantly extends the service life of stainless steel belts.
Production of Oxide Ceramic Matrix Composites by a Prepreg Technique
Authors: Guglielmi P.O. , Nunes G.F. , Hablitzel M. , Hotza Dachamir , Janssen Rolf
Published: August 2012

Ceramic matrix composites (CMCs) were developed to overcome the intrinsic brittleness and lack of reliability of monolithic ceramics. Their major advantages include high temperature capability, light weight, corrosion resistance and adequate damage tolerance. All-oxide Ceramic Matrix Composites (OCMCs) offer essential advantages with respect to long time stability in oxidizing atmospheres, when compared to their non-oxide counterparts. Nevertheless, there is at present almost no production concept which meets the requirements in view of cost and performance for these materials. This work aims at producing OCMCs by means of a more flexible production route. This is achieved by integrating well-known powder metallurgy routes with the prepreg technique, used at present for producing commercial high performance polymer matrix composites. The processing consists of the following steps: (a) infiltration of commercial alumina fiber fabrics (3M NextelTM610) with a liquid suspension of the matrix material; (b) lamination of the pre-infiltrated fiber textiles with a paraffin-based suspension for the formation of prepregs; (c) layup of prepregs; (d) warm-pressing for the consolidation of the green body; (e) debinding and (f) reaction bonding and/or sintering for synthesis of the oxide matrix. Pure alumina or Reaction Bonded Aluminum Oxide (RBAO) can be used as matrix materials and damage tolerance is achieved by the porous, weak-matrix approach. Microstructural analysis of a pure alumina composite fabricated by this route show good infiltration of fiber bundles and proves the good adhesion of prepregs during processing. Average strength value of 199 MPa in fiber direction is in good agreement with values presented in the literature for OCMCs produced by other techniques.
RBMAO: A Novel Route for Porous Matrix Composites
Authors: Berti L.F. , Rambo Carlos R. , Bazzo E. , Janβen R. , Hotza Dachamir
Published: August 2012

This work reports on a novel route to produce porous matrixes for fibre reinforced ceramic matrix composites. This route relies on a reaction bonding process involving an intermediary carbide phase with subsequent oxidation. A slurry was prepared by mixing mullite powder, phenolic resin and aluminium powder in ethanol, which was used to impregnate Nextel fibres 610 (3M) by dip coating under ultrasonic vibration. The composites were vacuum-dried and submitted to a thermal treatment that consisted of a reaction step at 1250°C in Ar-atmosphere to convert the phenolic resin into carbon, which reacted with aluminium, leading to a carbide phase. The samples were then oxidized at 1250°C for 1h in air and subsequently sintered at 1300°C for 2h. Mechanical properties of composites and of matrix were determined at room temperature by 3-and 4-point bending tests, respectively. The microstructure of the composites was evaluated by optical-and scanning electronic microscopy, which revealed an apparent flawless microstructure.
Composites of Cement Matrix Containing Residue of PET Bottles and Stone Dust Replacing the Conventional Materials - Physical Chemistry and Mechanics Evaluations
Authors: Pereira Vilany Santana , da Silva Morais Crislene Rodrigues , Rodrigues Pablo Araújo , Aquino José Lourenço S. , Filho Francisco Ferreira Dantas
Published: August 2012

The development of technologies that use clean energy and integrated waste management of the residues domestic and industrial aimed a sustainable engineering in the socio-business concepts is an urgent necessity. This present paper has as objective the production of cement composites trace 1:1,2:0,8 (cement : dust stone: gravel) replacing the sand and dust stone for PET waste in the levels of 3, 6, 9, 12 and 15 %, to evaluate the aging time. The materials were characterized using thermal analysis, FTIR and the composites by particle size analysis, unconfined compression strength, among others. The particle size analysis allowed the calculation of fineness modulus, which was 2.59, 1.66, and 3.99 for the dust stone, gravel and PET, respectively. There was a decreasing trend of resistance with the PET increasing in the composition.