bluuebunny/crossref_metadata_2025 huggingface dataset:
Static Stiffness Analysis of a Novel Parallel Manipulator
Authors: Li Yun Feng , Li Chang Feng , Qu Dong Sheng , Zou Ling
Published: August 2012

One novel 6-DOF parallel manipulator with hooke hinges is presented to provide precision positioning in this paper. The geometric parameters and spatial architecture of kinematic pairs will influence the system stiffness directly, which impact indirectly the characteristics such as supporting capacity, driving burden and so on. The elastic model of the single chain based on the stiffness equation is presented and the stiffness model of the whole structure is constructed via the principle of virtual work. The static stiffness properties of the manipulator are discussed and the problem of finding the minimum and maximum stiffness and the directions in which they occur for a manipulator in a given posture is addressed. An example is given and the results show that static stiffness properties can be used to guide the optimal design of the structure.
Research on Visualization System of Virtual Workshop Based on Virtual Reality Technology
Authors: Wan Xiao Jing , Sun Wen Lei , Cui Quan Wei
Published: August 2012

Virtual reality technology could take advantage of computers to generate a more realistic simulation environment, this article achieved that the secondary development of a virtual workshop visualization system from the point of virtual reality technology. Practice has proved that the system not only supports the real-time interaction, automatic roaming, roaming manually, real-time information inquiry, but also supports the virtual external hardware devices such as data gloves and position tracking equipment, etc.
Research on Virtual Reality Technology Based the Application System of the Pumping Unit
Authors: Cui Quan Wei , Sun Wen Lei , Wan Xiao Jing , Wang Chun Xiang
Published: August 2012

The pumping unit is designed and assembled collaboratively by using virtual reality technology combining with the UG and VAPlatform. A simulation roaming system of the field scene is established which uses Nvision platform and 3Dmax. The system is based on the real working condition to enhance the sense of reality, uses interactive roaming mode, observes the objects in the virtual environment from any point of view, and reproduces the working state of the pumping unit in the oil field, which provides reference value for the complex mechanical production.
The Study of Collaborative Design System Based on Android
Authors: Pan Dan Dan , Sun Wen Lei , Peng Yun , Zhao Qun
Published: August 2012

With the popularization of the modern smart mobile devices and the embedded graphic program method, co-design in a mobile phone or tablet PC may be a possible technique. Although the embedded modeling software still not very commonly used, 3D graphics processing capabilities of embedded systems provided an environment for viewing 3D product model on mobile devices. In order to make the product of design and manufacture more convenient and meet market demand, the study designed a kind of co-design system software on android intelligent device. This paper is based on the use of intelligent mobile devices into a mechanical and electronic product collaborative design system.
Research and Application on Manufacturing Scientific Data Sharing Service Customization
Authors: Zheng Yu , Ni Yan Rong , Ma Deng Zhe
Published: August 2012

In order to satisfy the needs of fast and convenient customization of manufacturing scientific data sharing service, the data service customization process and its key technologies were studied. First the data resource model and the customization oriented professional data service model were studied. Then the processes of service customization, from resource registration, service definition, service parsing, to service generating, were analyzed. The parsing engine based on service parsing technology and incubator based on service generating technology was emphasized. Finally the prototype system was developed and validated by an example.
The Research of Resource Scheduling Based on Genetic Algorithm
Authors: Yuan Zhi Ling , Yuan Yi Ping , Yang Meng
Published: August 2012

Job Shop scheduling problem, the essence of which is the resources scheduling problem, which has been proved to be a complete NP-hard problem. It has importantly realistic effect on further research, and has become a hot spot of research now. According to the practical Job Shop, as equipment resources are not unique, there are several machine tools with high frequency, while the number of that of low frequency is only one; the working procedure of processing components are also quite different, so we have put forward the Genetic Algorithm considering the sequence and, simultaneously, the machine choice. For reaching the shortest producing period, this method adopts Gemini string to encode, combining with the characteristics of the resources scheduling problem, and designs the unique way of Crossover and Mutation, meanwhile, it shows that the algorithm is effective through a specific example simulation analysis.
Study on Regulated Pressure Vacuum Casting Method for Larger & Thin-Wall Castings
Authors: Zhang Zhuang Ya , Zhang Hai Guang , Xu Nan Nan , Lv Tian , Liu Yuan Yuan , Hu Qing Xi
Published: August 2012

Aiming at the problem that current vacuum casting method lack of the filling ability in filling large & thin-wall castings. Therefore, a regulated pressure vacuum casting method is proposed, which using regulated pressure to improve the filling ability. The process and mechanism for regulated pressure vacuum casting method is presented and proved it through the home-made V450N-VD vacuum casting prototype. The results show that the regulated pressure vacuum casting method has higher filling capacity and can provide higher negative pressure during the whole filling process. So regulated pressure vacuum casting method has profound development potential.
Vibration-Wear Characteristics of Cutter in High Speed Ball-End Milling Hardened Steel
Authors: Jiang Bin , Zhao Pei Yi , Song Ji Guang , Chen Bo , Bai Jin Xuan
Published: August 2012

For vibration-wear characteristics of cutter in high speed ball-end milling hardened steel, established vibration-wear model of high speed milling cutter according to the principle of friction work, researched the influence of basic frequency and multiplication frequency of cutter vibration on its wear, and analyzed the interaction between cutter vibration and wear. By means of changing cutter extended length, rotation speed and cutting depth, made the change of cutter vibration, analyzed the influence of cutter vibration on its fretting and impact wear, explored the evolution process of composite vibration wear of cutter. Results show that the interaction between fretting fatigue wear and the impact wear make for cutter vibration-wear, lead to the increase of cutting force and vibration amplitude, and further increase the interaction strength of vibration and wear.
Development of Pharmaceutical Production Management System Based on RFID
Authors: Ren Nai Fei , Wang Xiu Jie , Li Yang
Published: August 2012

Pharmaceutical is related to people's health and life safety directly, we can track and control pharmaceutical safety and quality by constructing the traceable system of pharmaceuticals whole life cycle, including raw materials, production, transportation and storage. This paper develops a pharmaceutical production management system based on RFID technology, the system realizes the drug security by RFID, puts forward a pharmaceutical coding method according to EPCgloble, constructs a scheduling method and a monitoring of the pharmaceutical production process, and then it will be traceable for the information of pharmaceutical production process.
The Intelligent Design of the Gear Reducer
Authors: Fang Jian Jiang , Qi Wen Jun
Published: August 2012

The gear drive is the wide range of applications and is particularly important as a form of mechanical transmission, but the design process requires large amounts of data access and computation. In the paper, computer integrated technology and object-oriented technology is used to research and develop the intelligent design of Straight gear reducer system with user-friendly interactive platform, easy to use, high design efficiency and reliable data.
Study on Key Technologies of Web Parts Library System Development
Authors: Li Peng Cheng , Sun Wen Lei , He Li , Wang Hong Wei
Published: August 2012

Through the development of the web parts library system, this paper intensively studies the secondary development technology of Pro/E in asynchronous mode on the .NET platform, using C # programming language, dynamically browsing three-dimensional parts technology on line and on-line parameterized driving technology, and with ADO.NET network programming technology, achieves on-line connecting database. With all the key technologies researched above, it demonstrates the feasibility of achieving each function and process of web parts library system.
Research on Analysis of Agricultural Engineering Information System
Authors: Li Hui Jing , Tong Guang Ji , Cao Ying
Published: August 2012

With the development of society and the progress of science and technology, the agricultural engineering information grows fast. For this, this paper takes agricultural engineering information system as the object, analyzes the agricultural engineering information system by SWOT analysis method. Then proposed the countermeasure of establish agricultural engineering information system operation mechanism.
The Application of Cellular Particle Swarm Optimization Algorithm on the Model of Cooperation Degree and Professional Degree
Authors: Zhang Li , Hai Ji Zhe
Published: August 2012

Collaborative Decision-Making (CDM) is an important problem of optimization including collection of opinions and evaluations of results. In this paper, CDM is based on the model of cooperation degree (CD) and professional degree (PD). CD describes how close experts opinions are to each other. PD describes how close experts opinions are to the ideal result. This paper proposes a cellular particle swarm optimization (CPSO), hybridizing cellular automata (CA) and particle swarm optimization (PSO) to solve the CDM model. In the proposed CPSO, a mechanism of CA is integrated in the velocity update to modify the trajectories of particles to avoid being trapped in the local optimum. Theoretical studies and numerical experiments are conducted to compare the proposed algorithm with PSO and GA. According to the experimental results, the proposed method performs better than other two algorithms in this model solution.
The Implementation of IEEE 1588-2008 Precision Time Protocol on the STM32F107
Authors: Yang Guang You , Zheng Yi , Ma Zhi Yan , Hu Xin Yu
Published: August 2012

High precision clock synchronization is the basis for all applications in network-based distributed motion control system. To solve this problem, the clock synchronization principle is analysed; the initialization process of STM32F107VC PTP(Precision Time Protocol) hardware unit is introduced, and the process of capturing time stamp by PTP hardware unit, as well as clock adjustment mechanism, is in-depth dissected. PTPd v2 clock synchronization is realized in STM32F107VC platform supported by LwIP protocol stack. The results indicate that it is able to achieve an accuracy of less than 260ns clock synchronization based on STM32F107VC PTP hardware unit.
Cleft Lip Surgery Program Scheduled Based on Finite Element Analysis
Authors: Qi Wen Jun , Zhao Tang Min , Hu Li
Published: August 2012

In the paper, the force is analyzed and compared using the finite element analysis software ANSYS Workbench for the same patient with cleft lip using different programs, pre-surgery program is scheduled according to the results, the program will be determined by the surgery depends mainly on the physician's experience into a scientific analysis for cleft lip surgery, a way is studied to determine the scientific and reasonable cleft lip surgery program.
Simulation of Generator with Moving Mesh
Authors: Yang Lu , Sun Ming Li , Tang Liang Dao , Cheng Guang Ming
Published: August 2012

This paper shows how the circular motion of a rotor with permanent magnets generates an induced EMF in a stator winding. The generated voltage is calculated with moving mesh in COMSOL Multiphysics as a function of time during the rotation. The model also shows the influence on the voltage from material parameters, rotation velocity, and number of turns in the winding.
The Research on a New Feeding Device of Low-Temperature Deposition for Fabricating Tissue Engineering Scaffolds
Authors: Liu Ying , Fang Shu Hui , Han Zheng Zhong , Liu Da Li , Liu Yuan Yuan , Hu Qing Xi
Published: August 2012

Low-temperature deposition manufacturing (LDM) has been proven as an effective bone scaffold preparation process, but its further application has been seriously hindered by the existing material over-accumulation problem. In view of the over-accumulation problem of the traditional pneumatic extrusion material feeding way, designed and developed a feeding system based on pneumatic-extrusion and valve-control, which can achieve rapid pressure/relief, Combined with the inflation / deflation time calculation method of fixed volume container for analysis and calculation. A unified data management method of the material feeding device and a regulation scheme of the controller are given. Experimental results show that, by adjusting parameters, the feeding system based on pneumatic-extrusion and valve-control can achieve rapid gas pressure/relief, the flux has been well controlled, the over-accumulation on deposition path at the end has been eliminated, which lead to effective guarantee of scaffold forming quality.
Study on Low-Temperature Deposition Manufacturing Process Parameters of Three-Dimensional Chitosan Scaffold
Authors: Liu Yuan Yuan , Fang Shu Hui , Han Zhen Zhong , Liu Ying , Liu Da Li , Hu Qing Xi
Published: August 2012

From the perspective of forming bone scaffold, the technologic parameters of LDM which have important influence on the shape of the deposition material are studied. Through building experimental platform and using chitosan solution as experimental material, the influence of the temperature and the layer height on the lap of every fiber layer are firstly discussed in detail. Besides, the effects of nozzle diameter, the velocity of receiving device, the pressure of feeding device are also discussed. Then the above mentioned process parameters are all optimized, which make the forming mechanism of LDM to be clear. Finally, based on the optimal parameters, the scaffold with self-designed pore size and a high degree of pore interconnectivity, which meeting the requirements of the structure of tissue engineering are fabricated.
Simulation of Tensile Test of the 1/2Y Welded Joint Made of Ultra High Strength Steel
Authors: Galkiewicz Jarosław
Published: August 2012

The detailed analysis of the tensile properties of the 1/2Y welded joint made of ultra-high strength steel S 960 QC was carried out. The analysis concerned various parts of welded joint and has been carried out with the help of both experiment and numerical simulation. Results were compared with the data measured using the ARAMIS system. The purpose of the analysis was to provide the constitutive relations for detailed analysis of the welded joint by finite element method.
Residual Stresses in Steel-Titanium Composite Manufactured by Explosive Welding
Authors: Karolczuk Aleksander , Kluger Krzysztof , Kowalski Mateusz , Żok Fabian , Robak Grzegorz
Published: August 2012

The main aim of the paper is determination of residual stresses in explosively welded steel-titanium bimetal. The analysis considers two bimetallic specimens: before and after the heat treatment. In residual stress determination the hole drilling method along with finite element analysis were applied. The results show different residual stress states depending on the heat treatment. The obtained results are confirmed by thermal stress calculation.
Influence of Temperature on the Cyclic Properties of Martensitic Cast Steel
Authors: Mrozinski Stanislaw , Skocki Radoslaw
Published: August 2012

This paper attempts to describe changes of the cyclic properties of martensitic cast steel in the function of the number of loading cycles under temperature of 25 and 600oC was made. The cyclic properties were described by means of three hysteresis loop parameters: stress amplitude, plastic strain amplitude, plastic strain energy. It was stated martensitic cast steel always undergoes clear softening which is independent of the temperature and level of total strain.
Use of Thermography for the Analysis of Strength Properties of Mini-Specimens
Authors: Lipski Adam , Boroński Dariusz
Published: August 2012

This paper presents sample applications of passive infrared thermography for research on temperature changes of mini-specimens resulting from monotonously increasing or cyclically variable mechanical load. The MFS system developed in the Department of Machine Design at the University of Technology and Life Sciences in Bydgoszcz (Poland) and designed for testing mechanical properties of microelements were used for tests. The MFS system ensures nanometric measurement accuracy of many static and fatigue-related material properties, including, i.a., static tension curves, cyclic strain curves, fatigue life curves as a function of force, stress and strain. Measurements of the mini-specimens temperature were performed using thermographic camera equipped with microscope lens. The tests have shown that research on the passive infrared thermography may be successfully applied for determining strength properties of materials in micro scale. The used research instrumentation is characterized by sufficient sensitivity and resolution (camera with the microscope lens), while the MFS system ensures accurate load and position control.
Criteria Evaluation for Fatigue Life Estimation under Proportional and Non-Proportional Loadings
Authors: Pejkowski Łukasz , Skibicki Dariusz
Published: August 2012

The paper presents the fatigue criteria, representing the integral criteria, most frequently reported in literature. They were verified for uniaxial loadings and for combined: tension-compression with torsion both proportional and non-proportional. The verification involved a comparison of the fatigue life reported based on the criterion with the experimental fatigue life.
An Experimental Investigation on Crack Initiation and Growth in Aircraft Fuselage Riveted Lap Joints
Authors: Skorupa Andrzej , Skorupa Małgorzata , Machniewicz Tomasz , Korbel Adam
Published: August 2012

Effects of variables related to design and production of riveted lap joints representative of longitudinal sheet connections for a pressurized transport aircraft fuselage were experimentally investigated. The specimens from an aircraft Al alloy D16 Alclad sheets of three different thicknesses (1.9, 1.2 and 0.8 mm) were assembled under load control using round head rivets and rivets with the compensator from a P24 Al alloy. For the joints from 1.9 mm thick sheets fatigue tests indicated a dependency of the crack initiation site and crack path on the squeeze force level and on the rivet type. At the same time, increasing the squeeze force led to improved fatigue properties of the joints, specimens assembled using the rivets with the compensator showing fatigue lives consistently longer than joints with the round head rivets. All observed trends have been explained based on hole expansion and load transfer measurements. For thin sheets connected using the round head rivets, local deformations and indentations under the driven rivet head promoted crack initiation and failure in the adjacent sheet. Fatigue test results indicated that the detrimental effect of this type imperfections could outweigh the benefits associated with a decrease in secondary bending due to thinning the sheets. The rivets with the compensator were observed to cause significant local imperfections beneath the manufactured head, which adversely affected the joint fatigue performance.
Modeling of Crack Growth in Steels
Authors: Jackiewicz Jacek
Published: August 2012

The paper discusses issues related to the damage accumulation and cracking in steels. Special attention is paid to the selection of appropriate methods in the modeling of progressive damage development. In special cases, the accumulation of damage and crack propagation may lead to the brutal destruction of machine parts. In addition, some attention was drawn to the conditions that can lead to this brutal destruction.
Description of Cyclic Properties of Steel in Variability Conditions of Mean Values and Amplitudes of Loading Cycles
Authors: Szala Grzegorz , Ligaj Bogdan
Published: August 2012

The work includes description of determination of two-parametric fatigue characteristics (TFC) on the base of experimental test results and description of mathematical models of these characteristics. Mathematical models were verified in C45 and 41Cr4 tests that are essentially different from the point of view of mechanical properties. On the base of analysis of verification test results there were determined ranges of applications of TFC models described in the work.
The Comparison of Cyclic Properties of X5CrNi18-10 Steel in the Range of Low-Cycle Fatigue in Conditions of Stress and Strain Control
Authors: Ligaj Bogdan , Szala Grzegorz
Published: August 2012

Service loading of constructional elements are caused by mass forces (dynamic loading) or displacement (kinematic loading). There are methods of estimation of cyclic properties of material based on stress or strain range control corresponding to the mentioned loading types. The paper includes an analysis of differences between diagrams determined in controlled stress and strain conditions as well as relations among: Wöhler curves (W), Manson-Coffin curves (M-C) and Ramberg-Osgood curves (R-O). Basing on the performed analysis there have been formulated conclusions that generally are on connecting loading character with conditions of determination of atigue curves.
Fatigue Test Welded Joints Steel S960QL
Authors: Goss Czesław , Marecki Paweł
Published: August 2012

Test results of residual stresses in welded butt joints were also presented. Finite Elments Methods and Jewdokimow and Lawrance’a methods of stress concentration factor αk calculation were comparative sumarized. Presents results is a part more considerable research attendant bridge MS-20.
Use of Silicon Nitride as an Additive in the Production of cBN Compacts for Cutting Tools
Authors: Skury Ana Lúcia Diegues , Chagas Shirlene , Bobrovinitchii Guerold Sergueevitch , Monteiro Sérgio Neves
Published: August 2012

Compositions of cutting tools based on cubic boron nitride phase added with different ceramics as binders have been the subject of several works. A major problem of these tools during machining of steel is the loss of cutting efficiency due the "chemical weathering" generated by the reaction between iron and cBN at the high temperatures reached by the machining operations. Aiming to eliminate these problems, this paper presents results on the development of composites obtained by sintering process at high pressures and high temperatures in association with a cyclic operation. Si3N4 was used as the binder agent. The compacts were analysed by x-ray diffraction as well as optical and scanning electron microscopy. The mechanical properties were evaluated by means of microhardness and fracture toughness tests. The degree of phase transformation of the Si3N4, the chemical reaction during the cyclic sintering process, and the sintering mechanism of the additive were discussed.
Improvement of Conventional Polycrystalline Diamond Composites by Nanodiamond Incorporation
Authors: Skury Ana Lúcia Diegues , Bobrovinitchii Guerold Sergueevitch , Monteiro Sérgio Neves , de Azevedo Marcia G.
Published: August 2012

Polycristalline diamond composites (PDC) obtained by sintering of micro sized diamond particles together with silicon as binder is a conventional superhard material for high speed cutting tools. nanosized dispersed diamond particles have been recently used as precursor for a new generation of superhard composites. In the present work, PDCs were produced by sintering at high pressure and high temperature using a mixture of micro and nanosized diamond particles for optimized compactation. The values of density and hardness as well the results of X-ray diffraction suggest a plastic deformation of the larger diamond particles. The compression strength of these composites was found to be close to that of natural diamonds.
Technical Performance of High Pressure and High Temperature Processed TiC Ceramic Tools
Authors: Bobrovinitchii Guerold Sergueevitch , Skury Ana Lucia D. , Monteiro Sérgio Neves , Azevedo Márcia G.
Published: August 2012

Non-oxide covalent ceramics such as TiC and TiN display hardness and thermal stability that favor their use as cermet insert for high speed turning operations. The objective of this work was to assess the properties of the TiC combined with W-Mo as binding matrix. The cermet sintering was carried out inside a toroidal anvil type of high pressure device up to 1.0 GPa of pressure and temperatures up to 1800°C. It was found that at 1400°C the Mo reacts with TiC forming Mo2C while at 1800°C the reaction with W forms WC. Moreover, the cermets density reaches 98% of the theoretically calculated value with strength of 942 MPa and Rockwell A hardness of 94. Efficient turning parameters are reported for machining operation using these cermets as tools insert.
Microstructural and Dielectric Properties of Conventional and Microwave Sintered CaCu3Ti4O12 Ceramics
Authors: Thomazini Daniel , Gelfuso Maria Virginia , Lima Gabriel Moreira , Eiras José Antônio
Published: August 2012

ts well known that CaCu3Ti4O12(CCTO) ceramic presents high dielectric constants, which makes it a strong candidate to be used in microelectronic devices. Several routes were proposed to obtain CCTO crystalline phase, influencing in microstructure and sintering conditions of the ceramics. In this study CCTO powders were produced by a new chemical route, providing reduction on hold time and sintering temperature. Furthermore, the sintering was performed in conventional and microwave oven that produced different microstructures. In this way, the microstructure and dielectric properties of these ceramics were evaluated and compared, showing the higher values of dielectric constant due to lower grain size and reduced copper-rich phase on grain boundary presented by microwave sintered ceramics.
Influence of Addition of Polymeric Precursors of Ceramics on Sintering of Al2O3
Authors: Godoy Ana Lúcia Exner , Bressiani José Carlos , Bressiani Ana Helena de Almeida
Published: August 2012

The effects of adding polymer precursor on the sintering behavior, microstructure and hardness of alumina ceramics have been studied. Polymer sintering aid polymethylhidrogensiloxane were used for alumina based ceramics sintered at 1650º C. The sintered materials were characterized using: (a) helium picnometry to determine apparent density; (b) x-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy and energy dispersive x-ray spectrometry to determine the microstructure and composition; (c) Vickers indentation analysis to determine the hardness and fracture toughness. The addition of polymethylhidrogensiloxane yielded alumina/mullite composites. The preparation of ceramic composites using small amounts of polymer precursors is suited for alumina based ceramics. The processing route being simple, it has the potential to enable the manufacture of complex shaped pieces.
Degradation of Y2O3-Stabilized ZrO2 Ceramics in Artificial Saliva: ICP Analysis of Dissolved Y3+ and Zr4+ Ions
Authors: Mukaeda L.E. , Taguchi Simone Pereira , Robin A. , Izario H.J. , Salazar F.S. , dos Santos Claudinei
Published: August 2012

ZrO2 ceramics are one of the most important materials used in dental prostheses production, due to their excellent mechanical resistance and chemical inertness in the mouth environment. Nevertheless, the combination of low pHs and fluoride presence is able to reduce the chemical stability of these ceramics. In this work, the resistance of commercial blocks of micrometric and nanometric sized Y2O3-stabilized ZrO2 ceramics (ProtMat Materiais Avançados® and Ivoclar®) was evaluated in Fusayama artificial saliva of different pHs with (and without) the presence of fluoride ions. The study was based on the analysis of the amount of Zr4+ and Y3+ ions dissolved in the artificial saliva after different exposure times using ICP OES technique. The XRD technique was also employed to investigate the phase transformations occurring during the degradation process in artificial saliva. The micrometric sized ZrO2 ceramics presented higher resistance in the artificial saliva than nanometric sized structures.
Extracellular Synthesis of Silica Oxide Particles by Fusarium oxysporum from Rice Husk Ash
Authors: Pineda Tatiana , Soares Carlos Henrique Lemos , Hotza Dachamir , Casas-Botero Ana Elisa , Ramírez-Carmona Margarita , Torres-Taborda Mabel
Published: August 2012

Extracellular synthesis of silica particles was carried out by Fusarium oxysporum mycelia using rice husk ash (RHA) as raw material. RHA before and after bioprocessing was analyzed by SEM and specific surface area. Dissolved silica was quantified using colorimetry. Incubation of rice husk ash with F. Oxysporum at 28°C and pH 6.8 indicated that 80% silica was dissolved and micrographs of RHA before and after reaction with fungi showed that the morphology of silica particles changed and the average size decreased (~600 to ~5 µm). Moreover, specific volume pore of particles was reduced from 0.026 to 0.013 cm3/g and surface area increased from 115 to 125 m2/g. Dissolved silica corresponds to 177 m2/g. It is concluded that synthesis of oxide materials using fungal biotransformation is a viable process to obtain added value products from agro-industrial waste materials.
Properties of Calcium Phosfate Cement with Addition of Dispersant and Hydrogel
Authors: Fernandes J.M. , Coelho W.T. , Thürmer Mônica Beatriz , Vieira Rafaela Silveira , Santos Luis Alberto
Published: August 2012

The calcium phosphate cements (CPCs) have attracted great interest for use in orthopedics and dentistry as replacements for damaged parts of the skeletal system,showing good biocompatibility and osseointegration. These characteristics allow its use as a bone graft.Several studies in literature have shown that the addition of polymeric additives has a strong influence on the mechanical properties of cement. The low mechanical strength is the main impediment to a broader use of calcium phosphate bone cement (CPCs) as implant material. The aim of this work was evaluate the strength of a CPC based on α-tricalcium phosphate, with polymeric additions. CPC was synthesized and sodium alginate were added (1%, 2% and 3% by weight) and ammonium polyacrylate (3%; dispersant) in aqueous solution. Specimens were molded and evaluated for density, pH, porosity, in vitro test (Simulated Body Fluid),crystalline phases and mechanical strength. The results show the increase of the mechanical properties of cement when added with sodium alginate and dispersant.
Effect on Mechanical Strength of Tricalcium Phosphate Cement by Additions of Sodium Alginate
Authors: Coelho W.T. , Fernandes Juliana Machado , Vieira Rafaela Silveira , Thürmer Mônica Beatriz , Santos Luis Alberto
Published: August 2012

The Calcium Phosphate Cement (CPC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry due to its biocompatibility, bioactivity and osteoconductivity, and form a paste that can be easily shaped and placed into the surgical site. However, CPCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. In order to assess the strength and time to handle a CPC composed primarily of alpha phase, were added sodium alginate (1%, 2% and 3% wt) and an accelerator in an aqueous solution. The cement powder was mixed with liquid of setting, shaped into specimens and evaluated for apparent density and porosity by Archimedes method, X-ray diffraction and compressive strength. A significant increase in compressive strength by adding sodium alginate was verified.
Evaluation of α-Tricalcium Phosphate Cement Obtained at Different Temperatures
Authors: Vieira Rafaela Silveira , Coelho Wilbur Trajano Guerin , Thürmer Mônica Beatriz , Fernandes Juliana Machado , Santos Luis Alberto
Published: August 2012

The calcium phosphate cements (CPCs) based on α-tricalcium phosphate (α-TCP) are highly attractive for use in medicine and odontology, since they have similar chemical and phase composition of mineral phase of bones (calcium deficient hydroxyapatite (CDHA)). However, one of the biggest difficulties for use of this type of cement is its low mechanical strength due to the presence of undesirable phases, such as β-tricalcium phosphate. The route for obtaining α-TCP is at high temperature by solid state reaction, mixing calcium carbonate and calcium pyrophosphate. The aim of this work was to obtain calcium phosphate cements with improved strength, by studying the obtaining of α-TCP at temperatures of 1300, 1400 and 1500°C. The samples were analyzed by crystalline phases, pH, setting time, particle size, in vitro test (Simulated Body Fluid), porosity, density and compressive strength. The results show that the synthesis temperatures influence strongly the phases of powders obtained and the mechanical properties of cement, being unnecessary quenching for obtaining pure α-TCP.
Molecular Sieves (MCM-41, Al-MCM-41) Characterization Using Different Silica Sources
Authors: Santos José Otávio Peroba Nascimento , de Miranda Rafaela Pereira Roque , Figueiroa Deivid Sousa , Pereira Carlos Eduardo , de Sousa Bianca Viana
Published: August 2012

Research, synthesis and catalytic application of molecular sieves areas has been constituting a large field of development and prominence in recent decades, due to the large potential of these materials in respect of theirs catalytic properties. The need for costs reduction in the production of these structures, has encouraged the search for new sources of reactants which could provide an equal application of these sieves together with low costs. This work has the aim to obtain and to characterize molecular sieves type MCM-41 and Al-MCM-41 using new routes of synthesis. The molecular sieves MCM-41 and Al-MCM-41 were synthesized using the molar composition: 1 Si02: 0.04 Al03: 0.24 CTAB: 0.3 Na2O: 150 H20. Through the thermal analysis it was possible to observe different peaks related to the presence of volatile materials and the structural director in the materials. Using techniques of characterization like XRD was possible to confirm the formation of the mesoporous structures using the amorphous silica derived from rice husk ash as a silica source.
Preparation and Characterization of Zeolite ZSM-5 in the Template: Effect of Crystallization Time on the Structure and Textural Properties
Authors: Sousa Aécio B. , dos S. Barbosa Antusia , Freire Rodrigues Meiry Glaúcia , Laborde Herve M.
Published: August 2012

The preparation of ZSM-5 templates in the absence of organics is an area of high technological impact. These are responsible for the enhancement of the final products (zeolites). Therefore, the preparation of zeolites in the absence of template allows a compromise covering the low cost and environment. This study aimed to investigate the influence of synthesis time in the preparation of ZSM-5. This zeolite was prepared by hydrothermal synthesis, using as co-template (C2H5OH) and addition of seeds. The times of synthesis used were 3 to 5 days. The solids were characterized by XRD, BET and Spectroscopy in the infrared region. Through the results obtained with XRD, it was observed that all samples showed characteristic peaks of MFI structure of the group at intervals of 2θ = 7-9° and 23-25°, showing no presence of secondary phases. BET surface area showed a corresponding literature. The infrared showed bands characteristic of ZSM-5.
Evaluation of the Bioactivity Behavior of a 48 Wt %SiO2 Bioglass through Experiments in Simulated Body Fluid
Authors: Borges Roger , da Silva Antônio Carlos , Marchi Juliana
Published: August 2012

Among bioceramics materials, bioglasses which exhibits either a bioactive or resorbable behavior has been studied for many applications, such as bone substitutive and regeneration. When in contact with body fluid, the bioglasses can induce the formation of a hydroxyapatite surface layer. In this paper, we studied the bioactivity of a bioglass containing 48 wt %SiO2, 27 wt% Na2O, 19 wt % CaO and 6 wt %P2O5. After fusion and annealing, the samples were immersed in SBF for different periods, up to 14 days. The samples were characterized through XRD, DRIFT and SEM before and after bioactivity experiments. The overall results suggest the formation of a surface layer of consisting of hydroxyapatite, which was crystallized within seven days after in vitro experiments, leading to a suitable bioactivity. Moreover, the samples showed a glass network with high cohesion due to calcium addition, leading to materials with high corrosion resistance.
Study of Carbon Influence on Magnetic Properties of Metal Injection Molding Nd-Fe-B Based Magnets
Authors: Lopes Leonardo Ulian , Carvalho Matheus Amorim , Chaves Rafael Sottili , Trevisan Marcel Pittol , Wendhausen Paulo A.P. , Takiishi Hidetoshi
Published: August 2012

In this work, Metal Injection Molding (MIM) process was applied to manufacture Nd-Fe-B magnets, where carbon residues were quantified. In a separated test, controlled additions of carbon were added prior to sintering in the conventional processing of Nd-Fe-B magnets, aiming to simulate the binder residues with more accuracy. The carbon contents in the sintered magnets were related to final magnetic properties such as remanence and coercivity. It was found that the rare-earth content in the alloy influence the threshold where further additions of carbon will degrade coercivity. This study gives directions on developing binder systems and debinding processes, focusing on reaching adequate carbon levels to maximize final magnetic properties.
Comparative Analysis of Sintering Mn0.65Zn0.35Fe2O4 Ferrite by Microwave Energy and N2 Atmosphere
Authors: Santos R.L.P. , Tavares M.M. , Cornejo Daniel , Kiminami Ruth Herta Goldsmith Aliaga , de Melo Costa Ana Cristina Figueiredo
Published: August 2012

Research in Mn-Zn ferrites have been growing in recent years, mainly because of the properties in high frequency application such as high saturation magnetization, low core losses, which are sensitive to the structure, processing conditions, such as sintering temperature, time and atmosphere. This study aims to evaluate the microstructure and magnetic characteristics Mn0.65Zn0.35Fe2O4ferrite sintered in N2atmosphere and to microwave energy at 1200°C/2h. The samples were compacted by uniaxial pressing at 200 MPa and sintered in a microwave oven with a heating rate of 50°C/min and sintering time of 30 min. For samples sintered in N2atmosphere was used heating rate of 5°C/min with sintering time of 2 hours. The samples were characterized by apparent and bulk density, XRD, SEM and magnetic measurements. The results indicate the formation single phase of Mn-Zn ferrite for sample sintering in N2atmosphere, and to sintering by microwave oven observed the phase ferrite Mn-Zn with trace of secondary phase hematite. The density and saturation magnetization were 3.14 and 3.12 g/cm3, 5 and 83 emug-1for the samples sintered by microwave energy and N2atmosphere respectively.
Synthesis and Characterization of Cu0.5Zn0.5Fe2O4 Ferrite for Application as a Soft Magnetic Material
Authors: Costa A.C.F.M. , Costa A.D.S. , Viana K.M.S. , Portela F.A. , Paiva-Santos O. , Kiminami R.H.G.A.
Published: August 2012

This work involved the synthesis and characterization of Cu0.5Zn0.5Fe2O4ferrite powders prepared by combustion reaction for use as soft magnetic materials. The powders were characterized by nitrogen adsorption (BET), XRD, Rietveld refinement, SEM, TEM and magnetic measures. The results indicate that the combustion reaction yielded crystalline powders containing spinel ferrite as the primary phase and traces of Fe2O3as secondary phase. The crystallite size and lattice microdeformation calculated from Rietveld refinements were 36 and 0.24 nm, respectively. The micrographic analysis revealed particles smaller than 100 nm and fine particle agglomerates. The particles were approximately spherical and their size, calculated by TEM, was 29 nm. The magnetic parameters indicated that the Cu-Zn ferrite powders presented closed hysteresis loops and soft magnetic properties.
Preparation of NiFe2O4 and ZnFe2O4 Samples by Combustion Reaction and Evaluation of Performance in Reaction Water Gas Shift Reaction - WGSR
Authors: Santos P.T.A. , de Melo Costa Ana Cristina Figueiredo , Andrade Heloysa Martins Carvalho
Published: August 2012

This paper aims to synthesize and characterize nanosized nickel and zinc ferrites (NiFe2O4and ZnFe2O4) samples by a combustion reaction method, using glycine as fuel. The performance in HT-WGRS reaction the samples was investigated. The results showed that the combustion reaction was effective in the production of major phases of the spinel ferrite (crystallite sizes of 44 and 27 nm) and presence of the secondary phases, such as Ni and ZnO, with surface area 3 and 115 m2/g for NiFe2O4and ZnFe2O4, respectively. HT-WGSR activity was achieved (80%) to NiFe2O4ferrite in the temperature range of 300 - 500°C.
A Model for the Hysteresis Curves of Soft Magnetic Materials
Authors: Sampaio da Silva Fernanda A. , de Campos Marcos Flavio
Published: August 2012

A model, based on hyperbolic tangent curve, was found to be able to reproduce several different types of magnetization curves of soft magnetic materials. The model is especially suitable for curves with sigmoid shape. The model is compared with experimental data for bonded soft iron powders, and also other ferromagnetic materials (1045 steel). Three adjusting parameters were used in the original hyperbolic tangent equation. Each parameter has different physical meaning.
Combustion Synthesis of ZnAl2O4 Catalyst Using Glycine as Fuel for the Esterification and Transesterification of Soybean Oil: Influence the Form of Heating
Authors: Coutinho Juliana Pimentel , Silva Mirele Costa , Meneghetti Simoni Margareti Plentz , Leal Elvia , de Melo Costa Ana Cristina Figueiredo , de Freitas Normanda Lino
Published: August 2012

The aim of this work is to evaluate the esterification and transesterification activity of ZnAl2O4catalysts obtained by different ways of heating during the combustion synthesis using glycine as fuel. Samples were prepared according to the propellants and explosives theory using a vitreous silica crucible as container, and as heating source, plate, muffle furnace and microwave oven. After synthesis, the samples were structural and morphologically characterized by: XRD, nitrogen adsorption and carbon content analysis, and employed in the esterification and transesterification reactions, the percentage of biodiesel formed (FAME) was determined by gas chromatography. The samples obtained on the plate, muffle furnace and microwave showed that even using different heating ways, led to the formation of ZnAl2O4as majority phase, with crystallite sizes of 11, 15 and 10 nm, respectively. The samples present values of surface area ranging from 16 to 77 m2/g, particle size from 17 to 81 nm, and carbon content lower than 11%. The forms used for heating influenced the esterification and transesterification reactions, showing that there was a gap in the production of biodiesel, which is a promising indication that this material has potential to be used as catalysts on the biodiesel production.
Combustion Synthesis of LSM Powders from a Precursor Solution with Mixed Fuels
Authors: Tarragó Diego Pereira , Malfatti Célia de Fraga , de Sousa Vânia Caldas
Published: August 2012

For the combustion synthesis of strontium doped lanthanum manganite (LSM), different fuels can be used influencing the phase formation and also the powder morphology. Both are important features that can improve the material performance when used in a solid oxide fuel cell cathode. Urea and sucrose are fuels used to synthesize distinct LSM powders, thus the purpose of this work was to mix these fuels in order to obtain nanocrystalline LSM powders with a differentiated morphology, more convenient for the desired application. After calcination at 750°C for 3 hours the powder generated a pure phase LSM X-ray diffraction pattern and the micrographs taken in the transmission and scanning electron microscopes revealed a very peculiar morphology with specific surface area (BET) of 13 m²/g. Calcination led to a single phase and more crystalline material but showed no influence in the powder morphology.
Processing and Characterization of Al2O3-YAG Composite
Authors: Lima E.S. , Louro Luis Henrique Leme , de Campos José Brant , de Avillez R.R. , Monteiro Sérgio Neves , da Costa Célio Albano
Published: August 2012

Oxide ceramics show better oxidation resistance at high temperatures than other ceramics; however they are more susceptible to plastic deformation at elevated temperatures [. If their high temperature mechanical properties could be improved, they would be expected to open a wide range of applications as structural material [2, 3]. Several studies have revealed [4, 5] the potential use of YAG oxides as reinforcing component oxide in a ceramic matrix. Both YAG and Al2O3 have similar thermal expansion coefficient and they are chemically stable because of their low O2 vapor pressure. In addition, there is no solid state phase transition as the temperature rises, but the eutectic reaction at 1826°C with Al2O3 molar concentration of 81.5% and 18.5% for Y2O3 which enable a fusion processing, turning the Al2O3-YAG composites very attractive. This eutectic reaction is possible in the restrictive composition from 18.5 to 20.5 mol% Y2O3 [6].
Synthesis of Zeolitic Materials Using as a Source of SiO2 and Al2O3 Calcined Kaolin Waste
Authors: Hildebrando Edemarino A. , Angélica Rômulo S. , de Freitas Neves Roberto , Valenzuela-Díaz Francisco Rolando
Published: August 2012

This paper has as main objective synthesize zeolitic materials in hydrothermal conditions using as the predominant source of Si and Al a waste in powder generated from kaolin processing industries for paper-coating from the Brazilian Amazon region, thus transforming a material of low commercial value in another with higher added value, and can thus be used in future in adsorption and catalysis. For this were tested compositions of the mixture with different molar ratios of Na2O/Al2O3and SiO2/Al2O3considering the effects time-temperature of crystallization. The starting material and the phases formed as synthetic products were characterized by XRD, SEM and FTIR. The results show that the methodology developed with metakaolinite from a thermically activated kaolin waste at 700 º C for 2h reacting in alkaline medium in the presence of an additional source of silica, zeolitic phases were obtained with structure FAU-type and GIS-type in the samples synthesized.