bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties of Co-Extruded Aluminium-Steel Compounds
Authors: Thürer Susanne Elisabeth , Uhe Johanna , Golovko Oleksandr , Bonk Christian , Bouguecha Anas , Behrens Bernd-Arno , Klose Christian
Published: July 2017

Within the scope of the Collaborative Research Centre (CRC) 1153 novel process chains for the production of hybrid solid components by Tailored Forming are developed at the Leibniz Universität Hannover. The combination of e. g. aluminium with steel allows to produce hybrid compounds with wear-resistant functional surfaces and reduced weight. In these process chains, joining takes place as the first step to produce hybrid semi-finished products by friction welding, cladding, ultrasonic assisted laser welding or co-extrusion, which are subsequently subjected to various forming processes such as forging or impact extrusion. The coaxially joined hybrid semi-finished components investigated in this work were produced by means of the lateral angular co-extrusion (LACE) process using the aluminium alloy EN AW-6082 and the case-hardening steel 20MnCr5. These semi-finished products shall be suited to produce hybrid bearing bushings by die forging in a subsequent process step. Initial investigations for the determination of the process parameters and the appropriate tool geometry were made using a steel rod. In future investigations, a steel tube will replace the steel rod in order to produce hybrid semi-finished products, which can be fully integrated into the process chain. The mechanical properties of the profile were determined at different positions along its length. For this purpose, the quality of the joining zone between aluminium and steel as a function of the profile position was examined by means of push-out tests. Moreover, the mechanical properties of the aluminium component’s longitudinal weld seam were determined by micro-tensile-tests.
Development of a High Pressure Die Casting Tool for Partial Integration of Glass Fiber Structures
Authors: Clausen Jan , Kelch Milan , Wöstmann Franz Josef , Busse Matthias
Published: July 2017

Due to the growing demand for lightweight solutions in a wide range of industries, the selection and combination of various materials is becoming more and more important. As a result, the need for suitable joining technologies is increasing along with it.
Within the DFG research group "Schwarz-Silber" ("black-silver"), Fraunhofer IFAM is investigating so-called transitional structures in cooperation with the University of Bremen. In this process, glass fiber structures are integrated into aluminum by a high pressure die casting process. These structures are used for the electrochemical insulation between aluminum and carbon fiber textiles, which are connected by textile processes in a subsequent production step. A solid hybrid structure is finally achieved through a resin-impregnation process. The key challenges are the positioning, pre-tensioning and infiltration of the glass fiber structures within the high pressure die casting process.
In order to meet these challenges, a customized die casting tool was developed within the project. With the aid of mold-filling simulations, the die system of the die casting tool was optimized to achieve better infiltration of the fiber bundles and to additionally support the position of the glass fibers in the casting process.
After the design of the molding tool, the implementation was carried out in collaboration with a toolmaker. In subsequent, up-to-date investigations, the positioning and infiltration of different variants of glass fiber structures is evaluated. The results are compared with previous attempts to position and infiltrate the glass fiber structures to assess the effect of the optimized newly designed tool.
Nozzle and Hot Runner Systems for Injection Moulding Machines for the Manufacturing of Moulded Thermoplastic Composite Parts with Skin-Core Structure (Sandwich Mouldings)
Authors: Reichert Volker , Nendel Wolfgang
Published: July 2017

Injection moulding of thermoplastic melts is based on the source flow. This principle allows for the production of mouldings in skin-core structure: the core enclosed on all sides by skin material may consist of a different or modified thermoplastic material. Generally, this method is referred to as co-injection or also sandwich injection moulding.Known applications of this method include processing of recycled material in the core and new material for the surfaces, foaming (chemically and physically) of the core material, processing of filled core material, e.g. Glass fibres and unfilled material for the surfaces. Other combined methods, e.g. with gas and water injection, are possible.The report describes the nozzles and hot runners developed by A&E Produktionstechnik Co. for the application of this method. Sample mouldings, produced and developed by customers and research cooperation partners, demonstrate the potentials and limits of the procedure in regard to the combination of different thermoplastic melts in a moulded part.
Influence of the Chemical Functionalisation of Glass Fibre Surfaces on the Mechanical Properties of Continuous Fibre Reinforced Thermoplastics
Authors: Böhme Constanze , Hase Katja , Tröltzsch Jürgen , Roth-Panke Isabelle , Helbig Frank , Nestler Daisy , Kroll Lothar
Published: July 2017

Continuous fibre reinforcements in thermoplastic composites require an enhanced adhesion to the matrix component, in order to effectively divert external forces from the matrix. Therefore different silanes as adhesion promoters are used as a part of the sizing. They operate as a connector to the matrix component. These silanes affect the sliding properties of the sizing during the production of the glass filaments in a negative way, in which case the proportion of the adhesion promoter in the sizing must be kept at a low level in order to maintain the processing speed in the textile production process. With the immersion bath method, it was examined whether the treatment of the surface of textile fabric after the textile production process with a silane-containing aqueous solution could solve these problems. Different silane concentrations and solvents were considered. After drying the textiles were processed during a two-step pressing process directly into a multi-layer organic sheet with a textile-based polypropylene matrix. The successful layering of the adhesion promoter on the glass fibre surface was verified by Fourier transform infrared (FTIR) spectroscopy. With thermogravimetric analysis (TGA), the thermal resistance of the adhesion-promoting layer for the subsequent pressing process could be shown. In order to examine the influence of the layer on the fibre/matrix adhesion within the composites, the Young’s modulus and flexural modulus of the composite panels were determined. Impact experiments were made to measure the required penetration energy and the energy absorption capacity of the composite panels. An optimum for the amount of adhesion promoter could be found. Exceeding the optimum amount of adhesion promoter in the solution led to a decrease in the mechanical properties of the composite.
FE-Based Design of a Forging Tool System for a Hybrid Bevel Gear
Authors: Behrens Bernd-Arno , Bouguecha Anas , Bonk Christian , Bonhage Martin , Chugreeva Anna , Matthias Tim
Published: July 2017

Multi-material solutions offer numerous benefits producing tailored-made hybrid components with enhanced application-optimized properties contrary to conventional monolithic parts. However, designing of corresponding manufacturing processes is often challenging due to various technical aspects. This paper represents a process route for the manufacturing of a hybrid bevel gear by means of tailored forming technology with a focus on die forging and describes the main challenges within the forming stage. Due to local material-specific properties, uncommon material flow and complex geometry of the final part, an individual forming tool system with a geared die was accurately designed. Besides the forming tool system, the FE-based design of the forging process as well as the necessary material characterisation will be presented. Finally, the initial results of the experimental forging investigations are shown.
Development of Nonwoven Preforms Made of Pure Recycled Carbon Fibres (rCF) for Applications of Composite Materials
Authors: Hofmann Marcel , Wenzel Dirk , Gulich Bernd , Illing-Günther Heike , Nestler Daisy
Published: July 2017

For the development of an efficient and economic recycling process of carbon fibers (CF) still many technological challenges have to be mastered. One of them is the removal of all extraneous natural and synthetic fibres, e.g. polyester sewing threads. The objective of the research was to develop an in-line process for the removal of those extraneous fibres, which result from mechanical processes such as tearing. A promising approach for the removal of extraneous fibres from cut-off carbon-fibre material (CF) has been identified, getting recycled carbon fibres (rCF). For that purpose, the use of modern laser technologies is particularly promising. However, the focus was not the development of new laser systems, but the adaptation of existing technologies and their integration into textile processing steps for carbon fibre recycling. In addition to the removal of the extraneous fibres, the degree of CF losses and quality degradation due to fibre damage have been analysed and compared with optimum fibre characteristics. The separation has been experimented and corresponding laser parameters have been defined. Finally, the obtained carbon-fibre material has been tested with regard to its processability in textile manufacturing processes (dry non-woven fabric production) up to carbon fibre reinforced plastics (CFRP). For the evaluation of the material for potential applications, test plates from irradiated and non-irradiated material have been used. The performed tensile and flexural tests have proved that the irradiated material has similar properties compared to the non-exposed one.
Mechanism-Oriented Characterization of the Fatigue Behavior of Glass Fiber-Reinforced Polyurethane Based on Hysteresis and Temperature Measurements
Authors: Hülsbusch Daniel , Jamrozy Michael , Mrzljak Selim , Walther Frank
Published: July 2017

In order to optimize resource efficiency, glass fiber-reinforced polymers (GFRP) have been implemented in recent years in a wide range of applications of transport industries. In this context, GFR-epoxy (GFR-EP) is currently being used mainly because of their sufficiently investigated properties and production processes. Polyurethane (PU), however, shows advantages in terms of energy efficiency and damage tolerance. The aim of this study is the characterization of the fatigue behavior of GFR-PU by stepwise exploration of damage development on microscopic level. Therefore, multiple amplitude and constant amplitude tests have been carried out. Hysteresis and temperature measurements were applied in order to investigate the damage processes and correlated with in situ computed tomography (CT) in intermitting tests. The damage development and mechanisms could be characterized and separated. The results confirm known GFRP damage characteristics, whereas also material-specific peculiarities regarding crack development could be revealed.
Acoustic Emission Analysis during Bending Tests of Continuous and Discontinuous Fiber Reinforced Polymers to Be Used in Hybrid Sheet Molding Compounds
Authors: Trauth Anna , Pinter Pascal , Weidenmann Kay André
Published: July 2017

Failure of fiber reinforced polymers is a complex interaction of different microstructural mechanisms. In order to assign those mechanisms to the macroscopic material response, in-situ methods as acoustic emission can be applied. This allows for the detection of initiation and growth as well as for the localization of damage in mechanically loaded materials. In this study, mechanical material testing of continuous and discontinuous fiber reinforced polymers was coupled with acoustic emission. Results have shown that different failure mechanisms resulting from different reinforcement architectures can be distinguished due to their acoustic emission signal. Based on experimentally captured acoustic emission signals, machine learning algorithms were applied to differentiate various failure mechanisms. This offers the possibility to investigate damage of hybrid continuous-discontinuous Sheet Molding Compounds exposed to bending loads.
Computed Tomography Experiments on a Laboratory Multipurpose Diffractometer
Authors: Dadivanyan Natalia , Götz Detlev J. , Beckers Detlef , Masiello Fabio
Published: July 2017

Applications of soft (Co and Cu X-ray tube) and hard (Ag X-ray tube) radiation in computed tomography experiments on a laboratory X-ray diffractometer are presented. Using low energy (<10 keV) X-ray sources provide the possibility to investigate objects made of light (organic) materials in more detail compared to the high energy application. In case of metal or heavy element containing composites high energy (~20 keV) X-ray sources allow to obtain full 3D information on the samples without destroying them. These measurements allow both qualitative and quantitative analysis of porous materials, samples with oriented components, and solid compounds.
Numerical Simulation of Low Velocity Impact on Pin-Reinforced Foam Core Sandwich Panel
Authors: Dimassi M. Adli , Herrmann Axel S.
Published: July 2017

The use of sandwich structures is well established in industrial sectors where high stiffness and strength combined with lightweight are required, like in marine, wind turbine and railway applications. However, the vulnerability of sandwich structures to low-velocity impacts limits its use in primary aircraft structures. Pin reinforcement of the foam core enhances the out-of-plane properties and the damage tolerance of the foam core. In this paper, a finite element model is proposed to predict the impact behaviour of pin-reinforced sandwich structure. An approach based on the building block approach was used to develop the model. Multi-scale modelling in the impact region that considers the delamination of the face sheet using cohesive zone elements was employed to increase the accuracy of the simulation. Impact tests were performed to validate the numerical model. A good agreement between numerical and experimental results in terms of contact-force displacement history and failure mode was found.
Simulation of the Influence of Embedded Inserts on the RTM Filling Behavior Considering Local Fiber Structure
Authors: Seuffert Julian , Kärger Luise , Henning Frank
Published: July 2017

Resin Transfer Molding (RTM) enables an intrinsic manufacturing of fiber reinforced composite parts containing integrated metallic inserts. The inserts are embedded into the fiber layers in the preforming stage of the process and therefore influence the following mold filling. The fiber structure around the embedded insert is strongly influenced by the insert resulting in high local variations of fiber volume fraction which changes the local permeability. This leads to an inhomogenic flow front and can even result in dry spots of the cured part. To predict the formation of air bubbles, a two-phase mold filling simulation is used under consideration of local fiber volume fraction. Local fiber structure is determined using CT-scans of manufactured parts with different orientations of the insert in relation to the preform and to the filling direction. The mold filling simulations allow the evaluation of different filling strategies and show a strong influence of the insert on the local flow front propagation.
Fiber-Reinforced Plastics with Locally Adapted Stiffness for Bio-Inspired Hingeless, Deployable Architectural Systems
Authors: Born Larissa , Körner Axel , Schieber Gundula , Westermeier Anna S. , Poppinga Simon , Sachse Renate , Bergmann Paavo , Betz Oliver , Bischoff Manfred , Speck Thomas , Knippers Jan , Milwich Markus , Gresser Götz T.
Published: July 2017

This paper presents results of the investigation of two biological role models, the shield bug (Graphosomaitalicum) and the carnivorous Waterwheel plant (Aldrovandavesiculosa). The aim was to identify biological construction and movement principles as inspiration for technical, deployable systems. The subsequent processes of abstraction and simulation of the movement and the design principles are summarized, followed by results on the mechanical investigations on various combinations of fibers and matrices with regard to taking advantage of the anisotropy of fiber-reinforced plastics (FRPs). With the results gained, it was possible to implement defined flexible bending zones in stiff composite components using one composite material, and thereby to mimic the biological role models. First small-scale demonstrators for adaptive façade shading systems – Flectofold and Flexagon – are proving the functionality.
Numerical Investigations of Internal and Residual Stresses in Aluminium-Polymer Laminate Foils during Stretch Forming
Authors: Müller Simon , Weygand Sabine M.
Published: July 2017

Aluminium-polymer laminate foils consisting of the layers PA, Al and PVC are used to manufacture high barrier pharmaceutical packages. These so called cold-formed blister packs are formed by stretch forming at room temperature. As due to the complex material structure the forming process is not yet well understood, the developers of cold-formed blister packaging machines design the punches for forming the cavities bigger than needed for the tablets being packed. Therefore, the aim of this work is to gain insight into the mechanical behavior of the composite during stretch forming. For this, internal and residual stresses in the layers are analyzed with the finite element method. With the help of a micromechanical and a stretch forming model simulations are performed. Furthermore, an analytical solution to calculate the internal and residual stresses during stretch forming the foil is presented. The calculation procedure can be used to determine stresses from surface strains which could be measured in forming experiments.
Material Characterization for Constituents of Fiber Reinforced Polymers by Experiments and Prediction of Effective Composite Properties
Authors: Goldmann Joseph , Kaestner Markus , Ulbricht Volker
Published: July 2017

The present contribution aims to investigate the ability of drawing predictive conclusions from homogenization in case of damage. Therefor, two topics will be addressed. On the one hand, material properties for the constituents on the microscale have to be derived, to render a predictive homogenization possible. The investigation at hand is concerned with glass fiber reinforced epoxy resin. In this example the properties of the fiber and the matrix have to be studied individually by experiments. Furthermore, the interface between both materials needs to be examined. To this end experiments on several models of single fiber composites have been developed in the literature. For the present material combination single fiber fragmentation tests and pullout tests have been conducted and evaluated. On the other hand, boundary conditions are necessary, that allow for the strain localization in a volume element without leading to spurious localization zones.
Toughening of Glass Fiber Reinforced Unsaturated Polyester Composites by Core-Shell Particles
Authors: Klingler Andreas , Sorochynska Liubov , Wetzel Bernd
Published: July 2017

This study focused on the examination of unsaturated polyester resin based continuous glass filament mat reinforced composites (GFRP) and the modification by core-shell rubber particles (CSR). The goal was to evaluate the effect of CSR toughening on processability, mechanical properties and impact strength as well as the interaction with inorganic color particles in the submicron range on the GFRP. The interlaminar fracture toughness GIc of the modified GFRP was improved by about 20% compared to the neat GFRP by using only 2 wt-% of the CSR modifier, while only marginally increasing the viscosity of the reactive mixture. The responsible mechanisms were found to be local shear yielding of the matrix and an improved fiber-matrix adhesion. The hybridization of inorganic color particles and CSR reduced the interlaminar fracture toughness of the laminate, which could be ascribed to the formation of pores due to the introduction of the oxide particles. However, the impact behavior of the GFRP was positively affected.
A Material Model for Prediction of Fatigue Damage and Degradation of CFRP Materials
Authors: Hohe Jörg , Gall Monika , Gauch Hannes , Fliegener Sascha , binti Abdul Hamid Zalkha Murni
Published: July 2017

Objective of the present study is the definition of a material model accounting for fatigue damage and degradation. The model is formulated as a brittle damage model in the otherwise linear elastic framework. A stress driven damage evolution equation is derived from microplasticity considerations. The model is implemented as a user-defined material model into a commercial finite element program. In a comparison with experimental data in the low cycle fatigue regime, a good agreement with the numerical prediction is obtained.
Highly Elastic Strain Gauges Based on Shape Memory Alloys for Monitoring of Fibre Reinforced Plastics
Authors: Mäder Thomas , Navarro y de Sosa Inaki , Senf Björn , Wolf Peter , Hamm Martin , Zoch Martin , Drossel Welf Guntram
Published: July 2017

Conventional strain gauges made of constantan or CuCr for instance have a low value for structural health monitoring issues in plastic composites. These strain sensor materials exhibit small elastic regions and show fatigue when dynamically loaded with strain levels over 0.3 percent. For this reason, these sensors would break or fail before the composite life-time and thus cannot be integrated into this kind of composite materials. Pseudoelastic thermal shape memory alloys are therefore used as strain sensors and integrated into composites in order to allow piezoresistive strain measurement and structural health monitoring in such materials. Thermal treatments are used to create sensor structures out of shape memory alloy wires. Pseudoelastic shape memory wires can be strained up to 8 percent repeatedly. Their gauge factor is higher than 5. Shape memory strain sensors are successfully embedded into glass fibre reinforced plastics and show a significant and reproducible resistance change when the composite is strained. The dynamic strength is magnificently higher compared to conventional strain gauges. Shape memory strain sensors are an efficient alternative to fiber-bragg-grating sensors and can potentially be used for strain measurements in different plastics and textile materials. Shape memory sensor structures can be embedded or applied and are good candidates for structural characterisation and monitoring applications.
Sensor Integration in Castings Made of Aluminum - New Approaches for Direct Sensor Integration in Aluminum High Pressure Die Casting
Authors: Tiedemann Rico , Pille Christoph , Dumstorff Gerrit , Lang Walter
Published: July 2017

The use of sensors for detection, measurement and evaluation of mechanical and thermal loads is well known and essential for the implementation of »Structural Health Monitoring« (SHM). For this, sensors are mainly used for condition monitoring of mechanical loads and their impact to the castings state, which is a decisive advantage for safety-related components. The use of sensors on the surface of metallic components, in particular of cast metal components made of aluminum, is still limited to the use of strain gauges. They are usually applied on the surface of the cast metal components and get fixed by adhesives. The idea is, to integrate the sensors directly during the aluminum casting process. Since integrated sensors are naturally protected against chemical and mechanical influences, furthermore the load can be measured directly at the point of interest inside the component. Measurement data can be recorded and provide a good data basis for future calculations and dimensioning of components, which is known as »Data Mining« or »Industrial Data Space«. New technology and material combinations, which allow the fabrication of sensors capable of withstanding force and temperature during the integration process in aluminum casting, are investigated.In this paper, the design and fabrication of a strain gauge printed on an aluminum sheet is shown. These sensor sheets get integrated in aluminum during high pressure die casting (HPDC) in a way that a specimen is build up. The specimen is characterized in a fatigue bending test and the sensor data was read permanently during this test. It is shown that the new approach with printed thick film sensors on aluminum substrate sheets works properly to withstand the heavy thermal conditions during high pressure die casting. The fabricated sensor is able to sense the mechanical tiredness and detects the fatigue of the metal matrix. This a first step to use such material integrated sensors in structural health monitoring applications.
Fiber/Matrix Adhesion in Glass Fiber Reinforced Inorganic-Organic Polyurea/Polysilicate Resins
Authors: Kopietz Mark , Bilgin Fatih , Grishchuk Sergiy , Wetzel Bernd
Published: July 2017

In this work newly developed phosphate-free polyurea/polysilicate resins (denoted as 2P) were explored and compared to market established 3P Resins® regarding their fiber/matrix adhesion with coupling agents introduced for further property improvement. Fiber/matrix adhesion was determined by macro mechanical test, i.e. interlaminar shear strength (ILSS), double-cantilever beam (DCB), Charpy impact, and tensile tests.It was demonstrated that 2P resins containing epoxidized linseed oil (ELO) replacing unfavorable organic phosphate esters in 3P Resins® as phase transfer agents nearly reach similar adhesion properties between fiber and matrix compared to established 3P Resins®. Additionally, some coupling agents were found to increase the ILSS by up to 26 %, the energy release rate by up to 7 %, the Charpy impact strength by up to 18 %, and the tensile modulus by up to 11 %.
Isoconversional Kinetic Analysis of Pyrolysis of Malt Waste
Authors: Silvério Beatriz Cristina , Franco Pedro Ivo Brandão e Melo , de Freitas Carolina Moreno , dos Santos Kássia Graciele , Antoniosi Filho Nelson Roberto
Published: July 2017

Locally available malt waste or brewers' spent grain, a by-product of brewing industry, was found to be a low cost and promising biomass for pyrolysis. A kinetic studied of pyrolysis of malt waste was investigated by non-isothermal thermogravimetric analyses (TG-DTG), applying slow heating rates, 10, 15, 30 and 50 K/min, and well-defined conditions. Activation energies and Arrhenius exponential factors were inferred by different estimation methods: Kissinger, Ozawa, Starink, K-A-S and. The methods presented energy activation values of 214 - 238.23 kJ/mol. The Literature studies found activations energies values similar to those found for sugarcane bagasse pyrolysis and other types of biomasses with predominance of hemicelluloses, cellulose and lignin, respectively.
Thermal Analysis and Analytical Pyrolysis of Three Types of Lignin
Authors: Santana Jr. José Alair , Carvalho Wender Santana , de Oliveira Tiago José Pires , Ataíde Carlos Henrique
Published: July 2017

There is a growing interest in new technologies for power generation, making use of renewable natural resources. Fast pyrolysis is an effective and promising process of thermal decomposition of organic materials. This study evaluated the thermal decomposition of three different types of lignin and investigated the composition of the volatiles formed during the analytical pyrolysis. The thermogravimetric analysis, which is a widely used analytical technique to observe the thermal behavior of materials, was used to investigate the decomposition of the samples at different heating rates. The micropyrolysis is a fast and reliable analytical technique that provides useful background information for development of the complex process production of bio-oil. This study evaluated the composition of the vapor formed during analytical pyrolysis at 450, 550 and 650°C. The curves obtained by thermogravimetric analysis indicate the degradation of all lignin samples takes place in a wide temperature range. Analytical pyrolysis tests for three types of lignin showed formation of phenolic compounds as most significant components.
Lab Scale Vibrating Screen Study on Operational Variables that Affect the Separation Efficiency
Authors: Guerreiro Fernando , Barbosa Vinícius , Gedraite Rubens , Ataíde Carlos Henrique
Published: July 2017

Vibrating screening is an equipment of simple design and execution, but its full description may be difficult to predict, considering that several variables can influence it. This work evaluates the effects of the independent variables: proportion of particles larger than the screen aperture size, average feed rate and g-force on the separation efficiency of coarse particles in a lab scale vibrating screening, where the material to be screened was phosphate rock, with density of 3.25 g/cm3 and particle size range of 0.6–600 μm. For this, a central composite design (CCD) was applied to quantify the main effects of the variables. As a result, the average feed rate was not relevant and the proportion of coarse particles and the g-force contributed positively to the increase of the efficiency. The point where the variables have their highest values, the maximum experimental efficiency was observed (94.93%).
A Fluid Dynamic Study in a Rotating Disk Applied in Granulation of Fertilizers
Authors: Vieira Neto José Luiz , Costa Dilson David Luiz , Souza Leticia Vitareli , Pires Ricardo Francisco , Souza Davi Leonardo , Silvério Beatriz Cristina , dos Santos Kássia Graciele
Published: July 2017

In fertilizers industries the granulation is an essential operation to form pellets with good quality. The granular product has improved handling, hardness, solubility, resistance to segregation and meets requirements such as the size, shape and particle size distribution through appropriate manipulation of the process variables. There are several types of granulators, however, this work is intended to study a granulator known as rotating disk, which promotes agitation of the particles by rotating around its axis. Although these devices are used industrially, cannot be found in the literature many details about the fluid dynamics in these operations. To study the fluid dynamics behavior of these particles on a rotation disk was analyzed the variables: rotation axis and filling degree. It was verified the existence of flow regimes which depends on these variables: rolling, cascading and centrifugation. Also, it was evaluated the dynamic angle of repose, that characterizes the rolling regime. This work aimed to obtain results of fluid dynamics that describe the behavior of solids flowing in a rotating disk. Thus, to meet the objectives of this work, simulations was carried out through the techniques of Computational Fluid Dynamics (CFD) and Discrete Element (DEM) to evaluate different parameter values: restitution coefficient (η), friction coefficient (μ) and the coefficient of elasticity (k) of the linear model "spring-dashpot" to find a good set of parameters that characterizes this system.
Global Reaction Model to Describe the Kinetics of Catalytic Pyrolysis of Coffee Grounds Waste
Authors: Batista Jr. Ronydes , Araújo Bruna Sene Alves , Franco Pedro Ivo Brandão e Melo , Silvério Beatriz Cristina , Danta Sandra Cristina , dos Santos Kássia Graciele
Published: July 2017

In view of the constant search for new sources of renewable energy, the particulate agro-industrial waste reuse emerges as an advantageous alternative. However, despite the advantages of using the biomass as an energy source, there is still strong resistance as the large-scale replacement of petroleum products due to the lack of scientifically proven efficient conversion technologies. In this context, the pyrolysis is presented as one of the most widely used thermal decomposition processes. The knowledge of aspects of chemical kinetics, thermodynamics these will, heat and mass transfer, are so important, since influence the quality of the product. This paper presents a kinetic study of slow pyrolysis of coffee grounds waste from dynamic thermogravimetric experiments (TG), using different powder catalysts. The primary thermal decomposition was described by the one-step reaction model, which considers a single global reaction. The kinetic parameters were estimated using nonlinear regression and the differential evolution method. The coffee ground waste was dried at 105°C for 24 hours. The sample in nature was analyzed at different heating rates, being 10, 15, 20, 30 and 50 K/min. In the catalytic pyrolysis, about 5% (w/w) of catalyst were added to the sample, at a heating rate of 30 K/min. The results show that the one-step model does not accurately represent the data of weight loss (TG) and its derivative (DTG), but can do an estimative of the activation energy reaction, and can show the differences caused by the catalysts. Although no one can say anything about the products formed with the addition of the catalyst, it would be necessary to micro-pyrolysis analysis, we can say the influence of the catalyst in the samples, based on the data obtained in thermogravimetric tests.
Production and Characterization of Porous Titanium Applied in Biomaterial
Authors: Bomfim Pâmela Karina S. , Cruz Israel A. , Fredericci Cátia , das Neves Mauricio David Martins
Published: July 2017

The development of materials with a porous titanium surface has been widely studied in the field of biomaterials due to the excellent biocompatibility, high corrosion resistance and combination of high strength with low density. Another relevant fact is that porosity allows bone tissue growth. However, the high reactivity in liquid state ends up hindering titanium fusion, so an alternative is the powder metallurgy (PM).The aim of this work was to produce porous titanium samples by conventional PM. Porous samples was characterized by porosity and microstructure (optical microscopy - OP and scanning electron microscopy SEM), crystaline phase (X-ray diffraction –XRD), mechanical properties (three point bending test) and cytotoxic test. The results showed the presence of alpha phase, a decrease in the elasticity modulus, increase in average pore size and samples exhibited no toxic effects.
Microstructure and Oxidation Resistance of Mechanically Alloyed and Sintered Ni-Nb and Ni-Nb-Ta Alloys
Authors: Ferreira Lucas , Rezende Stephania Capellari , Pinto da Silva Antonio Augusto Araújo , Poirier Gael Yves , Coelho Gilberto Carvalho , Ramos Alfeu Saraiva
Published: July 2017

The present work reports on the microstructure and oxidation resistance of Ni-25Nb, Ni-20Nb-5Ta and Ni-15Nb-10Ta alloys produced by high-energy ball milling and subsequent sintering. The sintered samples were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive spectrometry, and static oxidation tests. Homogeneous microstructures of the binary and ternary alloys indicated the major presence of the β-Ni3Nb compound as matrix, which dissolved large amounts of tantalum. Consequently, the β-Ni3Nb peaks moved toward the direction of smaller diffraction angles. Iron contamination lower than 6.7 at.-% was detected by EDS analysis, which were picked-up during the previous ball milling process. After the static oxidation tests (1100°C for 4 h) the sintered Ni-25Nb, Ni-20Nb-5Ta and Ni-15Nb-10Ta alloys presented mass gains of 31.5%, 30.5% and 28.8%, respectively. Despite the higher densification of the Ni-15Nb-10Ta alloy, the results suggested that the tantalum addition contributed to improve the oxidation resistance of the β-Ni3Nb compound.
Effect of Fe Addition on Microstructure and Properties of Powder Metallurgy Ti35Nb10Ta Alloy
Authors: Amigó Angèlica , Afonso Conrado Ramos Moreira , Amigó Vicente
Published: July 2017

The high contents of noble refractory elements of Ti35Nb10Ta (wt.%) alloy difficult the diffusion of them. The stabilization of the β phase can be favored by the addition of Fe in β-Ti alloys. In this work, elemental powders mixture with different contents of Fe (0, 1.5, 3.0 and 4.5 wt.%) were used. These powders were compacted with uniaxial pressure of 600MPa and sintered at 1250°C in high vacuum. The porosity obtained after sintering shows a dependence on the particle size of iron used, and homogeneous pores distribution was observed. The analyzed microstructure mainly corresponds to β-Ti phase, with small fractions of α phase appearing at grain boundaries, which decreases with increasing of Fe content. The microstructure showed good compositional homogeneity of Fe and Ta and some lack of diffusion related to large amount of undissolved Nb particles. Addition of Fe lead to a decrease in bending strength of Ti35Nb10Ta alloy.
Synthesis and Characterization of Ag-TiO2 Nanocomposites for Possible Use as Biocide
Authors: de Freitas Rosa Paula , Alves Ana Clara Matias , Lopes Aguiar Mônica , Bernardo André
Published: July 2017

Currently nanoparticles are being widely used because they have large surface area and pronounced effect relative to the properties of the material. Silver and Titanium Dioxide nanoparticles, for example, have pronounced biocidal effects, since they can inactivate certain enzymes and alter the DNA synthesis of some microorganisms. It is expected that a composite of the nanoparticles of the two metals can further increase the biocide power. This way, the study of the synthesis and characterization of nanocomposites becomes highly relevant. The aim of this work was to synthesize Ag-TiO2 nanocomposites and to characterize them in order to contribute to the understanding of the preparation of nanocomposite materials. In this study, we used a sol-gel method, which makes use of a reduction reaction using sodium citrate as the reducing agent, and titanium butoxide, acetic acid and silver nitrate as starting material. After being synthesized, the nanocomposite was analyzed with the techniques of Scanning Electron Microscopy coupled to energy dispersive X-ray detector (SEM / EDS) and X-ray Diffraction.
Structural and Magnetic Characterization of LaFe1-xAlxO3 (x = 0 and 0.2) Orthoferrites Synthesized by Gelatin Method
Authors: Pimentel Patrícia Mendonça , Dutra J.L.S. , Lima A.C. , Araújo J.H. , Bagnato Osmar Roberto , Costa Asenete Frutuoso , Oliveira Rosane Maria Pessoa Betânio
Published: July 2017

The rare-earth orthoferrites (LnFeO3) are promising materials for various applications, such as chemical sensors, cathode for SOFC, catalysts, among others. In general, these oxides are synthesized at temperatures higher than 700 °C. In this work, nanocrystalline LaFe1-xAlxO3 (x=0, x=0.2) powders were synthesized by a method that uses gelatin as organic precursor and heat treated at 400, 600 and 800 °C. The structural and magnetic characterization of powders was carried out by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Morphological analysis was performed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD patterns revealed the formation of orthoferrites single phase since 400°C. The powders exhibited weak ferromagnetic behavior at room temperature where the values of saturation magnetization, remanence and coercivity varied with the doping and heat treatment temperature.
Study of the Effects of SiO2 Nanoparticles Concentration on the TiO2 Nanoparticles Suspensions Stabilization
Authors: de Oliveira Elizabeth Mendes , Paresque Mara Carolina do Carmo , da Silval Leonardo Martins , Lopes Luiz Carlos Rolim , de Castro Jose Adilson
Published: July 2017

TiO2 nanoparticles (NPTiO2) suspensions are in several ecosystems and residue treatment processes or disposal systems due to their large industrial use and handling. The interactions of the NPTiO2 with NPSiO2 have special interest due to their strong ability to maintain high TiO2 nanoparticles concentration in suspension and promote nanoparticles clustering. These characteristics are used either in cleaning systems or in production of nanoparticles solution for several applications in the food industry or medicine. In this study, suspensions of NPTiO2 and NPSiO2 are synthetized and their stabilizations are discussed. A base TiO2 nanoparticles suspension was synthetized and the initial concentrations of SiO2 nanoparticles (NPSiO2) were changed in order to determine the effects of presence of SiO2 nanoparticles on the stabilization and clustering size. Zeta potential and concentrations measurements were carried out throughout the time and correlated with the initial concentrations of the base suspensions. In this study, the concentrations, zeta potential and pH are measured to estimate the stability of the suspensions. The clustering size, obtained by nanoparticle tracking analysis (NTA), are also monitored and discussed. Results of column soil experiments are discussed and compared under similar conditions with literature data.
Thermal Influence on the Electric Parameters and Microstructures of Activated Powder Double Layer Supercapacitors
Authors: Fernandez Antonio Paulo Rodrigues , Galego Eguiberto , Faria R.N.
Published: July 2017

The effect of the working temperature on the capacity, internal equivalent serial resistance (ESR), equivalent parallel resistances (EPR) of some retail available electric double layer capacitors (EDLC) have been investigated. Standard capacities of 1.0 F at a maximum potential of 5.5 V were employed in this study. EPR values have been calculated using the self-discharge curves at temperatures above to the nominal maximum working temperature of the supercapacitors (~70°C). The ESR values were measured during charge using the constant current (1 mAF-1) interrupt method with oscilloscope. Microstructural characterization of the electrode material have been carried out using scanning electron microscopy (SEM) and chemical microanalyses employing energy dispersive X-ray analysis (EDX).
Longe Range Exchange Interactions in Sintered CuMn Alloys: A Monte Carlo Study
Authors: da Silva Jr. Amilton Ferreira , Martins Adriano S. , de Campos Marcos Flavio
Published: July 2017

It is presented a Monte Carlo (MC) study of the dependency of the magnetization of sintered CuMn alloys with the temperature and applied magnetic field using a RKKY function to model the Mn-Mn magnetic interaction. Two kinds of simulations were done: (i) simulations at zero magnetic field, where the energy is obtained as a function of the temperature and (ii) simulations at constant temperature, varying the applied magnetic field. For both kinds of simulations, the variations of the total energy and the magnetization with respect to the concentration x and the range of the interaction (cutoff distance) were calculated. These simulations indicate that the range of the interaction among the magnetic atoms has a significant impact on the thermodynamic properties of the studied alloy.
Influence of Functionality of Polyhedral Oligomeric Silsesquioxane (POSS) Dispersed in Epoxy Resin for Application in Hybrid Coating
Authors: Longhi Marielen , Pistor Vinicius , Zini Lucas Pandolphi , Kunst Sandra Raquel , Zattera Ademir José
Published: July 2017

The present study aimed to characterize the structure of nanocomposites obtained from the incorporation of three different polyhedral oligomeric silsesquioxane (POSS) in an epoxy resin. glycidylisobutyl-POSS, triglycidylisobutyl-POSS and glycidyl-POSS were added (5% by weight) in an epoxy matrix, diglycidyl ether of bisphenol-A (DGEBA), through a sonication process. The nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA). The XRD analysis presented a characteristic peak of POSS. The incorporation of glycidylisobutyl-POSS showed a significant increase in the value of glass transition temperature (Tg), being also the most effective in terms of dispersion. It should also be noted that glycidyl-POSS presented a greater influence on the thermal stability.
Valuation of Mechanical Properties and Microstructural Characterization of ASTM F75 Co-Cr Alloy Obtained by Selective Laser Melting (SLM) and Casting Techniques
Authors: Mergulhão Marcello Vertamatti , Podestá Carlos Eduardo , das Neves Mauricio David Martins
Published: July 2017

Advances in processes using the powder metallurgy techniques are making this technology competitive compared to the other traditional manufacturing processes, especially in medicine area. The additive rapid prototyping technique – selective laser melting (SLM) was applied in a biomaterial of CoCrMoFe alloy (ASTM F75), to study the mechanical properties and microstructural characterization in comparison between the conventional technique – casting. The gas atomized powder was investigated by their physical (as apparent density, bulk density and flow rate) and the chemical properties. The powder was analyzed using scanning electron microscope with energy-dispersed X-ray spectroscopy (SEM-EDS) and X-ray fluorescence. Specimens of standard samples were manufactured using these techniques to evaluate the mechanical properties as uniaxial tensile (yield strength, rupture tensile and elongation), transverse rupture strength and the micro hardness. The mechanical properties showed higher values in the SLM specimens than the casting specimens. Before the mechanical tests the specimens were examined using optical microscope (OM) and SEM-EDS. The micrographs revealed a microstructure with finer morphology in the SLM technique and the dendrites in the casting technique.
The Role of Sintered Al2O3-Nb2O5 Front Plate on the Ballistic Performance of Multilayered Armors
Authors: Monteiro Sergio Neves , da Silva Figueiredo Andre Ben-Hur , Lima Eduardo Sousa , Weber Ricardo Pondé , Louro Luis Henrique Leme , de Jesus Matos Marco Aurélio , Nascimento Lucio Fabio Cassiano , de Oliveira Braga Fabio
Published: July 2017

The performance of multilayered armor systems (MAS), composed of a front Al2O3-Nb2O5 ceramic plate followed by either plies of aramid fabric layer or curaua fiber reinforced polyester matrix composite layer and backed by an aluminum alloy sheet, was assessed. Ballistic impact tests were performed with actual 7.62 caliber ammunitions. Indentation in a clay witness, simulating a personal body behind the back layer, attested the efficacy of the MAS as an armor component. The ballistic efficiency of the front ceramic dissipating more than 50% of the bullet impact energy was associated with its capacity of fragmentation. As for the remaining energy, the lighter and cheaper curaua fiber composites were found to present a significant advantage as a possible substitute for the usual aramid fabric intermediate layer in MAS for individual protection against high speed projectiles.
Nanocomposite Polymer Clay to Support the Release of Drug
Authors: Oliveira Maria Jose A. , Lugão Ademar B. , Parra Duclerc F.
Published: July 2017

It is estimated that there are about 300,00 products named biomaterials that are used in the area of Health. Although they are widely used they have yet to be optimized for therapeutic use. Hence, the objective of this work was to develop nanocomposites hydrogels with poly (vinyl alcohol) (PVAl), glucantime, chitosan and synthetic clay Laponite RD, processed by gamma irradiation. To compare the behavior of drug release two systems were compared, PVAl / chitosan / clay and PVAl / clay. The morphology of the nanocomposites hydrogel was understood by using characterization techniques: X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM) and gel fraction. The release kinetics was analyzed at 37 °C for period of 48 hours. It was observed that the slower release of the drug occurs in the delivery system composed by PVAl / chitosan / clay with correlation of the crosslink type formed by chitosan.