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Disertaciones |
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1
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Davi Alves da Silva
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STUDY OF SURFACE PARAMETERS AND RESIDUAL STRESS IN ABNT 4340 STEEL HARDENED AFTER GRINDING USING DIFFERENT CUTTING FLUIDS
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Líder : LEONARDO ROBERTO DA SILVA
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MIEMBROS DE LA BANCA :
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ERNANE RODRIGUES DA SILVA
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LEONARDO ROBERTO DA SILVA
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MARCELO ARAUJO CAMARA
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Data: 05-feb-2018
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Resumen Espectáculo
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The characterization of topography of engineering surfaces is very important in applications involving friction, lubrication and wear. Although the large part of surfaces are specified by 2D parameters, they are often not sufficient to characterize a surface. Note a large effort is made by manufacturers and the scientific community to develop parameters and methodologies in order to characterize the surfaces for a specific functional application. In the grinding process high temperatures occur due to the removal of material and residual stresses are generated on the machined surface, affecting the mechanical behavior of the material. The performance of this process depends on the conditions of lubrication and cooling, preventing overheating of the part may interfere with the surface integrity of the piece. However, it is essential to make studies in search of alternative fluids in order to reduce these problems. This study aims to analyze the behavior of different cutting fluids (mix - 50% full fluid mineral oil base and 50% soybean oil; full fluid mineral oil base and synthetic cutting fluid) as well as the use of the technique Minimum Quantity Lubricant (MQL) in the grinding process of AISI 4340 hardened steel, through of the study of the surface parameters a of the residual stress. By means of the 2D, 3D parameters and residual stress, it was possible to obtain a good characterization of the ABNT 4340 steel surface, contributing to the understanding of the surface behavior in the dive grinding of process as well as the influence that the parameters and cutting fluids exercised on that surface process. In general, the best results in the evaluated parameters were verified for the integral cutting fluid, but a good option is the use of the mix fluid, since this one presented good results besides being a cutting fluid that can collaborate for an ecologically correct manufacture.
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2
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LUCIANO FERNANDES DE MAGALHAES
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Evaluation of iron ore tailings as supplementary cementitious material
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Líder : AUGUSTO CESAR DA SILVA BEZERRA
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MIEMBROS DE LA BANCA :
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AUGUSTO CESAR DA SILVA BEZERRA
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DOMINGOS SAVIO DE RESENDE
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MICHELLY DOS SANTOS OLIVEIRA
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SIDNEY NICODEMOS DA SILVA
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Data: 07-feb-2018
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The present work evaluated the possibility of the use of an iron ore tail as an addition to partial replacement of Portland cement in cementitious composites. The iron ore reject was processed and calcined in the temperatures of 500 and 750 °C. For analysis, scanning electron microscopy (SEM), laser granulometry, X-ray diffraction (XRD), X-ray fluorescence, thermogravimetric analysis (TGA) were performed. The inorganic and calcined iron ore tailings had their pozolanicity evaluated by the Luxan method. After a characterization, the tailings were used in the preparation of mortar specimens with 10, 20 and 30% weight substitution of Portland cement. The composites were submitted to compression tests, with ages of 3, 7, 28 and 91 days, flexural traction test, with ages of 28 and 91 days, and water absorption and sulfuric acid attack, with ages of 28 days. The results of the Luxan test showed that the calcined tailings have pozzolanic properties. The results of mechanical properties showed a decrease in resistance, but with values above 30MPa for 30% substitutions at 28 days. In relation to the acid attack resistance, a replacement of the cement by the tailings showed excellent results. In general, the use of iron ore tailings instead of cement in mortars is a viable alternative for the immobilization of this industrial waste.
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3
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STEFERSON FERREIRA DE OLIVEIRA
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Evaluation of tribological properties of SAE 52100 steel benefited and nitrided by electric discharges
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Líder : ERNANE RODRIGUES DA SILVA
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MIEMBROS DE LA BANCA :
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ELAINE CARBALLO SIQUEIRA CORREA
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ERNANE RODRIGUES DA SILVA
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MARCELO ARAUJO CAMARA
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ROGERIO FELICIO DOS SANTOS
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Data: 20-feb-2018
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SAE 52100 steel, usually supplied in the spheroid condition, is widely used in bearing components such as in ner and outer race ways, balls, roller sand needles. The develop ment of surface engineering and its new approaches to control friction and wear, allowed the increase of the useful life of components, in which the thermal and thermo chemical treatments stand out. The conventional electric discharge machining (EDM) machine, generally used in electro-erosion processes, was adapted in a new process called nitriding by electric discharges (NDE) that by means of a dialect trice concentration solution (30g / l) as a source of nitrogen composite of deionized water and urea, it was possible enrich the SAE 52100 steelsurfacewithironandchromiumnitrides.Thisworkinvestigatestheinfluenceofthe SAE 52100 steel alloyed with nitriding by electric discharges to obtain better properties due to wear. Slipping. Thus, the group of spheroid samples of the material as received was obtained and the group of samples benefited so that both were nitride by electric discharges and to correlates the properties to the wear with the mechanical properties of the material and formation of nitrites. Optical microscopy (OM) and scanning electron microscopy (SEM) techniques were used, revealing a uniform and hard e ned layer, as well as the increase of hardness in relation to the substrate evaluated by the Vickers (HV) micro hardness test. The formation of nitrides was confirmed by X-ray diffraction (XRD) and slip wear properties were measured by sliding distance friction coefficient curves performed on a pin-on-disctribo meter. Dispersive energy spectros copy (EDS) mapping was performe don’t racks formedduring thes lip we artest to identify the ad hesive wear mechanism. The work confirms that the surface modification increases the wear resistance because it contributed to the decrease of the friction, increase of the mechanical resistance and decrease of the wear rate of SAE 52100 steel.
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4
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Cintia Braga Briseno
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Influence of thermal processing in the development of multiconstituted microstructure and mechanical behavior of a TRIP assited steel
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Líder : ELAINE CARBALLO SIQUEIRA CORREA
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MIEMBROS DE LA BANCA :
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ELAINE CARBALLO SIQUEIRA CORREA
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NILTON DA SILVA MAIA
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WELLINGTON LOPES
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DAGOBERTO BRANDÃO SANTOS
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GILMAR CORDEIRO DA SILVA
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Data: 22-feb-2018
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TRIP-assisted steels shows great potential and applicability in automotive industry due to their excellent combinations of properties that allow the production of thinner sheets without compromising the performance of components. The excellent combination of high strength, ductility and crashworthiness observed in TRIP steels is related to the multiphase structure present in these steels, produced usually by a thermal treatment consisting in intercritical annealing followed by isothermal treatment in the bainitic transformation range. In this work the effects of the intercritical annealing and bainitic transformation temperatures, as well as the holding time at isothermal bainitic temperature, on the microstructure and mechanical properties of a TRIP-assisted steel were analyzed. Evaluations were conducted in terms of optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, hardness tests, tensile tests and analyzes concerning the work hardening behavior of the material by four different methods: Hollomon analysis, work hardening rate, instantaneous n value and Crussard-Jaoul analysis. Higher austempering times favored the formation of bainite with lath morphology and allowed greater retention of austenite, resulting in lowerhardness values and yield strength. Reduction of austemperingtemperature favored the refinement of the bainitic structure and resulted in lower retained austenite fractions, but with a higher carbon content. In general, the use of a lower intercritical temperature promoted lower hardness values due to the increase of ferrite proportion. As for the hardening methods used, the analysis concerning the instantaneous n value was the most adequate for the deformation behavior evaluation of the studied steel.
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5
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ISABELA CRISTINA DE OLIVEIRA ALENCAR
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Influence of mode of plastic deformation on the hardening of BH220 steel
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Líder : WELLINGTON LOPES
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MIEMBROS DE LA BANCA :
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ELAINE CARBALLO SIQUEIRA CORREA
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LEONARDO NEVES
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WELLINGTON LOPES
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Data: 23-feb-2018
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The hardening due to the restriction to the dislocation movement occurred by the Bake Hardening effect depends on several variables, such as the amount of .of pre-strain used during the heat treatment, which is similar to the operation of paint in automotive industry, and the direction of mechanical effort (anisotropy). Considering theses aspects, this work presents the study of BH effect of BH220 steel prestrained up to 1%, 2%, 3% and 4% of effective strain in samples cut at 0° and 90° of original rolling direction by tensile and shearing tests. The results indicated the influence of mode and amount of prestrain and direction on the BH effect
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6
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Ricardo Augusto Santos de Morais Gomes
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Recycling of automotive windshields: separation between PVB film and glass
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Líder : ROGERIO ANTONIO XAVIER NUNES
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MIEMBROS DE LA BANCA :
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ROGERIO ANTONIO XAVIER NUNES
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FLAVIO RENATO DE GOES PADULA
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WAGNER SADE
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Data: 26-feb-2018
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In 2010 around 60 thousands tons of windshield scrap were genereted in Brazil. However, only 8% of it was recycled. The current windscreens are made of laminated glass, which consists of two layers of glass and a layer of polyvinyl butyral (PVB) polymer in between. Both glass and PVB are recyclable, but they need to be separated, which hinders the recycling of windshields. The most used method of separation between PVB and glass is shredding. However, this process does not recycle 100% of the materials, as some of the shards of glass generated during the shredding are attached to the PVB, that generates a residue that’s contains 30% of the initial windshield mass. The objective of this work is to develop a process for complete separation between PVB film and the windshield glass, allowing the recycling of glass and PVB with no waste generation. Flat laminated glass proof body were used to establish the process parameters. The process was tested for windshield samples of Fiat Palio car, samples of Pilkington and Saint-Gobain Sekurit windshield brands were tested. The method developed in this study consists of three stages: glass fragmentation, thermochemical attack and removal of the remaining glass fragments. As a result, the PVB film was obtained without glass fragments, which allows recycling of both the polymer and the glass.
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7
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LOUDIANA MOSQUEIRA ANTONIO
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Influence of boron addition on the abrasive wear resistance of high chromium white cast iron
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Líder : IVETE PEIXOTO PINHEIRO SILVA
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MIEMBROS DE LA BANCA :
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ELAINE CARBALLO SIQUEIRA CORREA
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GERALDA CRISTINA DURÃES DE GODOY
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IVETE PEIXOTO PINHEIRO SILVA
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MARÍLIA MENDONÇA DE LIMA
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Data: 27-feb-2018
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High Chromium Cast Iron (HCCI) are ferrous alloys with high wear resistance. This is due to the high volumetric fraction of eutectic carbides (10 - 30%) that is distributed in a metallic matrix consisting of austenite, martensite and secondary carbides (MyCx). In this work the effect of the boron addition in the HCCI microstructure will be studied. To achieve this purpose, HCCI alloys of the ASTM A532 IIIA class were initially cast with and without boron addition. Subsequently, the alloys were thermally treated by annealing, destabilization and tempering. After the heat treatment, the samples were machined and cut. The following tests were performed: (i) metallography (sanding, polishing and Vilela etching) by optical microscopy, (ii) X-ray diffraction (XRD), (iii) chemical mapping and spot EDS analysis on constituents, (iv) Vickers hardness, (v) instrumented penetration hardness (vi) abrasive wear rubber wheel in severe and softer condition to evaluate the behavior of alloys (vii) profilometry and scanning electron microscopy of worn surfaces. The results showed eutectic microstructure for a sample without boron and hypereutectic microstructure for the alloy with boron addition and presence of secondary carbides after heat treatment for the alloy with boron. It was possible to relate the microstructure and hardness with alloys wear resistance. It was clear that the wear depends, in addition to the properties intrinsic to the material, of the conditions to which the material is subjected.
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8
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Joyce Christine Ribeiro
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Study of Bake Hardening effect for BH220 steel after a forming operation
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Líder : WELLINGTON LOPES
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MIEMBROS DE LA BANCA :
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ELAINE CARBALLO SIQUEIRA CORREA
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MARCELLO ROSA DUMONT
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WELLINGTON LOPES
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Data: 27-feb-2018
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The hardening of the Bake Hardening effect, BH, was studied in this work. This method is commonly used to increase the mechanical strength of steels in the automotive industry. Such a hardening mechanism depends on several parameters, such as the conditions used for the plastic deformation of the material, the temperature and time of the heat treatment, the chemical composition of the steel, among others. Considering this approach this work presented a Bake Hardening hardening study for the BH220 steel in the 1% preformed state after performing a stamping operation by analyzing the increase in mechanical strength. Samples were taken at 0 ° and 90 ° with respect to the rolling direction. Mechanical strength analysis was done using tensile techniques, with pre-deformations ranging from 0.4 to 3% and shear technique, with pre-deformations starting at 0.4% and reaching 11%. The results indicated a strong influence of the position of samples taken from the stamped product on hardening by hardening, as well as the plastic deformation applied to BH220 steel. Samples taken from the stamped product and tensile deformed in the 1% laminate condition revealed that the C direction of this product exhibited the greatest hardening by hardening. In the samples drawn at 90 ° DL, a differential mechanical behavior in traction and shear was observed: an increase of the BH effect was observed with the increase of the amount of pre-deformation while in shear, a decrease of the BH effect was observed with the increase of the amount of pre-deformation in shear. The responses of the material also varied by virtue of the mode of deformation applied. In terms of traction, the material was hardened, while in shear, there was softening for certain situations.
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9
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SAMUEL ALMEIDA FONSECA
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STUDY OF THE TECHNICAL FEASIBILITY OF RECYCLING AS A FRESH ASFALIC CONCRETE FOR COLD APPLICATION AS MATERIAL FOR MAKING PATCHES
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Líder : FLAVIO RENATO DE GOES PADULA
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MIEMBROS DE LA BANCA :
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CLAUDIO JOSE MARTINS
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FLAVIO RENATO DE GOES PADULA
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SIDNEY NICODEMOS DA SILVA
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Data: 26-mar-2018
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It is known that over the years, asphal tpavement be comes damaged dueto some factors, such as inclement weather, and there petiti vestresses caused by traffic. This leads to the appearance of defects in the surface of the pavement, such as cracks, sinkings, holes, amongothers. The main tenance of the pavements becomes necessary dueto this fact. As material for discarding road main tenance we have what we call asphalt concrete milling (CAF), the main material of this research. In addition to environ mental and economic is sues, the present work proposes there cycling of CAF with REOB (Re-refined engine oil bottom) and asphalt binder with SBS (CAP 65/80). It is intended here to produce a hot recycled asphalt mixture which can be applied cold (ambient temperature) in "borehole" operations. The CAF and the patching mixtures were characterized by MEV and EDS techniques, as well as the preparation of the specimens according to the Marshall methodology. The specimens were tested in the diametral compression, stability / creep Marshall test in order to evaluate if the mixture will be technically feasible for this type of application. The results showed that for 15% REOB the cold application is feasible, but such material needs to be applied in places where it is confined, as in the case of pothole patches, due to the significant reduction of the resistance. It was possible to verify that the reduction of the amount of REOB to 10 and 5% showed a relative improvement of the resistance, but a worsening of the cold material workability occurs.
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10
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GABRIELA MOREIRA LANA
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Synthesis, characterization and functionalization of magnetic particles for biomedical presentation
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Líder : SIDNEY NICODEMOS DA SILVA
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MIEMBROS DE LA BANCA :
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DANIELLE MARRA DE FREITAS SILVA
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HERMES DE SOUZA COSTA
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JURGEN VONDUNG
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PETER WILLIAM DE OLIVEIRA
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SIDNEY NICODEMOS DA SILVA
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Data: 26-mar-2018
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Superparamagnetic nanoparticles of iron oxides have been intensively studied for many industrial, environmental and biomedical applications. As biomaterials, nanoparticles have interesting properties for applications such as hyperthermia cancer treatments, contrast agents in MRI, controlled drug delivery, among others.In this project, superparamagnetic nanoparticles of iron oxides were synthetized by co-precipitation and coated with oleic acid in mono and bilayer. TEM analysis showed the particle size equal or inferior to 10 nm, magnetization analysis (VSM) proved the superparamagnetic character of the synthesized material and the results spectroscopies of Mössbauer and Fourier Transform Infrared (FTIR) confirmed the presences of phases and oleic acid molecules on the surface of the nanoparticles, recommending the potential of therapeutic use of nanoparticles of superparamagnetic magnetite.
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11
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Ismael Nogueira Rabelo de Melo
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Characterization and evaluation of the wear resistance of a high chromium cast iron alloy with niobium addition
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Líder : IVETE PEIXOTO PINHEIRO SILVA
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MIEMBROS DE LA BANCA :
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IVETE PEIXOTO PINHEIRO SILVA
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JOEL LIMA
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LEONARDO ROBERTO DA SILVA
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Data: 14-may-2018
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The high chromium cast iron (HCCI) has been widely used, especially in the mining industry when high abrasive wear resistance components are required. Many searches for higher wear resistance materials are being done. Niobium can be added to high chromium cast iron alloys by to increase wear resistance. The Distribution and Morphology of Niobium Carbides (NbC) should be used to optimize alloy strength, which is enhanced by the formation of these homogeneously distributed high hardness carbides. The present work evaluated the influence of 0.476% and 1.014% Niobium addition in microstructure and wear resistance in a 26% Cr - 2.8% C with Niobium in residual scale, with a content of 0.063% Nb alloy. It was verified a fine and hooked NbC carbides and some NbC rich Niobium layers around M7C3 carbides, being able to act as higher hardness coatings. Significant carbides volumetric fraction (CVF) reduction was verified with Niobium increase content, resulting in microstructures changes from eutectic to hypoeutectic morphology. The NbC carbides prevented the hardness reduction due to the CVF reduction in the heat-treated samples, however, the NbC carbines was not enough do prevent the hardness reduction caused by CVF reduction in the as-cast samples because of the higher sensitivity of hardness from CVF content in austenitic matrix. The hypoeutetic 1.014% Nb alloy presented equivalent mass losses to the eutectic with residual scale Niobium content alloy in tests with 45 N and 130 N loads. The results indicated mass loss reductions up to 32.17% with 0.476 % Nb content with statistically equivalent residual Niobium alloy hardness. The higher abrasive resistance alloy (0.476% Nb) presented the highest retained austenite content (36%), no Niobium addition alloy (32%) and 1.014% Nb with 30% of retained austenite content.
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12
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PEDRO HENRIQUE RIBEIRO XAVIER
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Analysis of the wear of the cutting tools in the milling of parts with different geometries.
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Líder : SANDRO CARDOSO SANTOS
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MIEMBROS DE LA BANCA :
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LEONARDO ROBERTO DA SILVA
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LUIS HENRIQUE ANDRADE MAIA
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SANDRO CARDOSO SANTOS
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YUKIO SHIGAKI
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Data: 22-may-2018
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The comprehension of the phenomena that occur during the machining allows the increase of the predictability of the process, leading to the increase of the productivity during the manufacture. Knowing the variables and the parameters of machining is very important to understand the behavior at the interface between the cutting tool and the workpiece. As an intermittent process, the milling exposes the cutting tool to cyclical variations of temperature and tension, generated by the rotation movement of the milling cutter during machining. This work has the objective of analyzing the wear of cutting tools in the front milling of parts with different geometries. These variations cause damages and wear, which can lead to fail and consequent end of tool life. Factors such as length and part geometry influence the number of tool inputs and outputs in the workpiece, increasing its wear. In this work, tests of frontal milling were carried out on two SAE 1045 steel bars with different geometries, keeping all cutting parameters constant. To differentiate them, channels were machined in one of them, respecting the total cut length, which was 300mm. After a defined amount of cut in and cut out, the tools underwent successive optical microscopy and mass gauging, in order to identify and characterize the present forms. Simultaneously, mechanical vibration signals were collected from the system composed of test specimens and cutting tools, with the purpose of ratifying the influence of the geometry of the parts on the evolution of tool wear. The data collected for each piece were arranged in graphs for a better understanding and comparison of the performance between the tools, and it was observed that the number of inputs and outputs of the tool on the part is the most relevant factor in the evolution of the wear. The tools used in the milling of the test pieces without channels were worn less than those used in the test pieces with channels.
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13
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DOUGLAS STHEFANNO DE SENA OLIVEIRA
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STUDY OF MECHANICAL BEHAVIOR OF METALLIC STRUCTURAL COMPONENTS IN A SHORT-TERM LOADING BY EXPERIMENTAL STRESSES ANALYSIS
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Líder : NILTON DA SILVA MAIA
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MIEMBROS DE LA BANCA :
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NILTON DA SILVA MAIA
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ELAINE CARBALLO SIQUEIRA CORREA
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EMERSON GIOVANI RABELLO
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LUIZ LEITE DA SILVA
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Data: 29-may-2018
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The developed study falls within the scope of dynamic loading of materials, which, in various situations, present distint behaviors in relation to static requests. In order to measure and evaluate the behavior of materials in impact tests, it is necessary to adopt specific procedures and detailed evaluations case-by-case, because there are many related variables, beyond the time of application of the load being very short. Overestimated values of mechanical stress, found using experimental stress analysis, in a drop test of a cask for storage and transportation of spent fuel from a nuclear research reactor, instigated the execution of this study, in order to better understand the phenomena and details related to the response of the extensometers to the short term loads. Thereby, it was verified in this work, by characterization of structural component and experimental stress analysis by extensometry, the level of mechanical stresses and the behavior of a coupled structural set of bar and weight, both made of the same metallic material, when subjected to different magnitudes of sudden efforts, so that both the influence of experimental measurement conditions and influence of specificities in situations of drop weight were observed in the results. The initial evaluations showed that the weight rebound in the flange located in the lower portion of the bar, causing two major peaks of mechanical stress in both components (bar and weight) arranged in a short time interval, of order less than 0.5 s. Moreover, it can be seen in all phases that the mechanical stresses in the Bar are, for the most part, higher than the calculated stresses in the Weight, with the stresses in the reduced sections being even greater, expressing the possibility of the reduced sections became stress concentrators in the bar structure. The work also revealed that the strain gage attachment terminals detached from the metal surface at various measurement points, with successive impacts during the test phases, damaging or eliminating the measurement capacity of these sensors, and, consequently, this phenomenon influenced the results in some steps in the calculation of the mechanical stresses and phase angles, so it’s believed to have certain relation with what happened in the cask prototype of the preliminary phase of studies.
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14
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Isabella de Souza Morais
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Sericiticphyllite as supplementary cementitious material
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Líder : AUGUSTO CESAR DA SILVA BEZERRA
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MIEMBROS DE LA BANCA :
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AUGUSTO CESAR DA SILVA BEZERRA
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IVETE PEIXOTO PINHEIRO SILVA
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PAULO RENATO PERDIGÃO DE PAIVA
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CRISTINA GUIMARAES CESAR
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Data: 20-jun-2018
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The sterile rocks in mines are extracted from the pit and disposed in piles, generating environmental liabilities and considerable costs. The sericiticphyllite represents much of the sterile in the iron mines of the Ferriferous Quadrangle. In order to reduce costs and improve concrete performance, the cement industry has used supplementary cementitious materials (SCMs) partially replacing clinker in Portland cement. A type of SCM is represented by pozzolans, which are materials that when finely milled can react with the cement forming compounds with binding properties. The present work evaluated use of sericiticphyllite in partial replacement of clinker in Portland cement. For this, the phyllite was initially characterized by granulometric analysis by wet sieving and thermogravimetric analysis (TGA).Based on these results,a granulometric reduction was carried out in an industrial scale pendular mill and thermal treatment at four different temperatures in an industrial rotary kiln, aiming to transform the little reactive phases of the phyllite into more reactive phases.The products were characterized by scanning electron microscopy (SEM), X ray fluorescence (XRF), laser granulometry (LG) and Xray diffraction DRX. For the characterization of the material as a pozzolan, hydration heat tests, electrical conductivity in sodium hydroxide solution and determination of the Portland Cement Performance Index were performed.New cements were produced by replacing 25% of a cement with reduced additions by milled phyllites with and without heat treatment. The properties of these cements were evaluated by mortars compressive strength tests at the age of 28 days as prescribed by the Brazilian cement standards. To complement the analysis, tests of flexural strength at 28 days, dry density, void ratio and water absorption were performed.The sericiticphylliteFRX composition indicated the oxides SiO2, Al2O3 e Fe2O3 and the XRD analysis indicated the presence of kaolinite, quartz, goethite, hematite and muscovite in the form of sericite, minerals formed predominantly by the oxides previously mentioned. The replacement of the Portland cement clinker by phyllite reduces the heat generated and dissipated in the hydration reaction of the cement pastes, reducing the porosity and increasing durability. The results of the electrical conductivity in sodium hydroxide solution and the determination of the Performance Index with Portland Cement showed that the phyllites heat treated at 700ºC and 900ºC have good pozzolanicity and meet the requirements of NBR 12653 for pozzolanic materials for the production of Portland cement. The milled sericiticphyllite with or without heat treatment has no influence on the flexural strength and causes a slight increase in the water absorption, it is believed that this absorption is due to the greater need of dewatering water caused by the increase of the surface area of the system due to the reduced granulometry of the phyllites when compared with the cement.All the phyllite samples tested can be used in pozzolan Portland cement compositions (CP IV) of strength class 32, according to NBR 5736 (ABNT, 1991).
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15
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JOSELLE FERRAZ CERDEIRA
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Study of recycled hot mix asphalt containing 100% of reclaimed asphalt pavement for execution of pothole repair
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Líder : FLAVIO RENATO DE GOES PADULA
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MIEMBROS DE LA BANCA :
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CLAUDIO JOSE MARTINS
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FLAVIO RENATO DE GOES PADULA
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SIDNEY NICODEMOS DA SILVA
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Data: 11-jul-2018
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Corrently the materials that make up the asphalt pavement are 100% recyclable. Hot recycling of Reclaimed Asphalt Pavement (RAP) has the potential to reduce the environmental impactsand above all the costsof construction of asphalt pavement. The present work proposes a study of the mechanical behavior of recycled asphalt mixtures using 100% RAP with the addition of rejuvenator agent - AR and asphaltic concrete pavement (ACP), besides the improved products of asphalt mixture as the surfactant additive –Evotherm and the rubber crumb as fine aggregate. The RAP was physically characterized, with its grain size compositions framed in the rolling layer, graduation “C” DNIT’s Standards. The dosages were based on rational (mechanistic) methodologies such as the Marshall methodology and the methodology proposed by Castro Neto, where the total binder contents were determined, considering the recovered binder and later performed the mechanical characterization using the Marshall Stability, Tensile Strength, Cantabrian test and Resilient Modulus survey. The Marshall Stability presented values between 10,124 and 28,912.46 N and the Tensile Strength for diametral compression test showed values between 0.68 and 2.89MPa.The results for modulus of resilience for the blends are the following values between 11.80 to 18.29GPa.This research has showed that it is possible to get an asphalt mix, from 100% RAP hot mix recycling, within the DNIT's normative requirements, for the execution of PotholeRepair,withemphasisonthe use of mobile miniasphaltplants.
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16
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RAFAEL MOUCO DE LUCCA BRAGA
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DEVELOPMENT OF THIN FILMS AND PRECIPITATED OF TITANIUM DIOXIDE BY SOL-GEL PROCESS AND HYDROTHERMAL TREATMENT
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Líder : ANGELA DE MELLO FERREIRA
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MIEMBROS DE LA BANCA :
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ANGELA DE MELLO FERREIRA
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GABRIELA CORDEIRO SILVA
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MARCELLO ROSA DUMONT
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PAULO RENATO PERDIGÃO DE PAIVA
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Data: 12-jul-2018
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Titanium dioxide (TiO2) systems have attracted interest in various research areas due to the numerous applications in different branches of the industry, such as: pharmaceutical, pigment, food, water purification, batteries, civil construction, and among others. In thin films it is the main material used in self-cleaning surfaces due to its photocatalytic activity, which results in photoinduced hydrophilicity, greatly improving water wettability. In order to present these characteristics, TiO2 must be in a specific crystallographic phase (anatase), which is usually obtained by high temperature calcination (between 400°C and 500°C). In view of the above, the applicability of a hydrothermal treatment to crystallize the titania under moderate temperatures was verified. The great advantage of the hydrothermal method, which consists in heating in a closed vessel under temperature and/or controlled pressure, is the low temperature processing, typically at 120°C, which allows the application of this technique in numerous substrates (polymers, tissues, among others) and consequently brings great energy savings. At this work, the influence of alternative routes for thin films and TiO2 precipitates obtained by the sol-gel process was investigated. Thin films with one, three and five layers of coatings were obtained by the dip-coating method and after obtaining the films the resulting solution was precipitated. Different treatments routes were evaluated, applying the steps of drying, hydrothermal treatment and calcination, as well as the combination of these. The thin films obtained were characterized for their homogeneity, morphology, transmittance and wettability. In the precipitates the crystalline phases, photocatalytic activity, specific surface area, pore size and volume distribution, crystal size and crystallinity were investigated. For the characterization, the following tests were used: scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) spectroscopy, X-ray diffractometry (XRD), optical microscopy (OM), X-ray fluorescence, nitrogen adsorption test, contact angle measurement on the goniometer and analysis of methylene blue decomposition. TiO2 precipitates with good photocatalytic activity, high crystallinity and with the peaks related to the anatase phase crystallographic planes were obtained by the route at low temperature with the use of the hydrothermal treatment. It was possible to identify in the samples, micro and mesopores, a surface area between 40m²/g and 180m²/g and average crystal size of 3nm for samples from the drying, 6nm hydrothermal and 12nm calcined. All the thin films produced by the different routes presented free cracks, with good homogeneity, transmittance between 60% and 90%, and hydrophilicity and superhydrophilicity (with a contact angle of less than 5°) after exposure to UV light.
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17
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Júnia Bicalho Duarte Rosa
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Surface enrichment of Ti-6Al-4V alloy with calcium and phosphorus by electrical discharge machining process
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Líder : EZEQUIEL DE SOUZA COSTA JUNIOR
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MIEMBROS DE LA BANCA :
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DANIELLE MARRA DE FREITAS SILVA
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ERNANE RODRIGUES DA SILVA
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EZEQUIEL DE SOUZA COSTA JUNIOR
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ROGERIO FELICIO DOS SANTOS
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SHEYLA MARIA DE CASTRO MÁXIMO BICALHO
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Data: 13-jul-2018
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Surface modifications of titanium and its alloys have been explored in order to improve osseointegration properties of these materials when used in construction of bone implants. Among the techniques used for this purpose is the Electrical Discharge Machining (EDM). With this technique, in addition to obtaining topography and roughness changes, it is possible to enrich the surface of desirable chemical elements for certain applications. The objective of this work is to functionalize the surface of the titanium alloy Ti-6Al-4V by the incorporation of phosphorus and calcium, aiming to improve the osseointegration characteristics of the material. In this sense, an EDM equipment was used as a source of electric discharges in the positive and negative polarities. As dielectric fluid, ionic solution based on calcium and phosphorus was used. The characterization of the surface and cross section was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS). The mechanical characterization was done by Vickers microhardness test and rugosity test. The wettability was evaluated by means of a contact angle test and the bioactivity of functionalized surfaces was analyzed by immersion test in SBF. The analyzes by SEM and EDS revealed the presence of calcium and phosphorus on the alloy surface, regardless of the polarity used, evidencing the effectiveness of the technique. Besides the surface, in both cases the elements are also present in the cross section, indicating the occurrence of the ion implantation phenomenon. The mechanical characterization showed a considerable increase in the hardness of the superficial region of the samples, for the two polarities. Significant increase of roughness was observed in the treated surfaces in relation to the untreated surface, especially in the surface treated in the negative polarity, which could be related to the possible osseointegration improvement after machining. The contact angle and SBF immersion tests indicated wettability and bioactivity improvement, respectively, suggesting potential increase of the enriched surfaces osseointegration with respect to the non-enriched surface, with emphasis on the machined surface in negative polarity.
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18
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PEDRO AUGUSTO RAMOS
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Evaluation of surface wear by abrasion of metallic materials for coating in the processing and extractionof mineral aggregates.
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Líder : ERNANE RODRIGUES DA SILVA
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MIEMBROS DE LA BANCA :
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ERNANE RODRIGUES DA SILVA
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MARIA CELESTE MONTEIRO DE SOUZA COSTA
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PEDRO PAIVA BRITO
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Data: 31-jul-2018
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The mineral aggregateshasinterestingcharacteristics for severalapplications, theirextractionandprocessingdependonthe mining processes, wherehigh wear ratesoccur. Wear as thevariablethatrepresentscost must beminimized in anyway, thusincreasingprofitabilityindicesanddecreasingmaintenance, therebyprovidinglongermachineandequipmentlife. In thiswork, a studywascarried out onthewearofmetalliccoatings, obtainedcommercially, being: high abrasionresistantlowalloyboronsteelswithdifferenthardness classes (AR) andhardfacingrichchromiumalloydepositedbywelding. Both coatequipment in thestagesof mineral extractionandprocessing. The coatingswereevaluated for theirmicrostructure, hardnessandchemicalcomposition. Abrasiveweartestswereperformedaccordingto ASTM G65 (Rubber Wheel) withquartzsandnumber 50, andtheabrasionresistancepropertiesofeachtestedcoatingwereanalyzed. The performances ofthecoatingstestedwereverifiedbymeansofthemassloss in theabrasivetestandbyscanningelectronmicroscopy, where micro wearmechanismswereidentified. The micro wearmechanismsobservedwererelatedtothemicrostructuretypeandhardnessofthecoatings, varyingbetweenmicro-cuttingandmicro-cracking. The highhardnesshardfacingrichchromiumalloypresentedhigherabrasiveresistancethanmartensiticlowalloyboronsteels, butpresenting a brittleandcrackingbehavior. Thiseffectcanaffect material performance underimpactoperatingconditions
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19
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Letícia Tasca dos Reis Corrêa
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Development and Characterization of 3D Scaffolds of Sodium Alginate and Gellan Gum
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Líder : HERMES DE SOUZA COSTA
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MIEMBROS DE LA BANCA :
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HERMES DE SOUZA COSTA
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CLAUDINEI REZENDE CALADO
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MARCELLO ROSA DUMONT
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Data: 14-ago-2018
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The intervertebral disc (IVD) is a complex and specialized fibrocartilaginous structure which is located between the vertebral bodies providing stability and the function of retain and dissipate mechanical loads evenly and allow the spine joint movements, , It consists of the nucleus pulposus (NP), circumferentially surrounded by the fibrous ring (AF). Degeneration of the IVD is a challenging clinical problem that requires measures for regenerating the injured disc. Biomaterials have demonstrated the ability to perform important functions in the treatment of IVD-related injuries, and the implantable devices from such materials have been studied by many researchers in recent years. Hydrogels have potentially viable elastic properties to treat IVD injuries. Currently hydrogels based on alginate and gellan gum are being increasingly used in tissue engineering. Gellan gum (GG) is an extracellular polysaccharide secreted by the bacterium Pseudomonas elodea, which depending on the processing is capable of forming a firm, transparent gel with characteristics that allow its use as matrix for cell growth as well as support and cellular sustainability. Alginate which is a natural polysaccharide extracted from seaweed, has mucoadhesive properties, and is biocompatible and biodegradable. The Tissue Engineering is a promising area to repair the damage by restoring viable or reconstruction of a tissue or organ through the development of three-dimensional porous matrices, commonly known as scaffolds. The aim of this study is to develop and characterize scaffolds 3D of Sodium Alginate (AS) and gellan gum (GG) to assess the possibility of its use as a biomaterial and assist in the tissue regeneration process, providing another treatment option to injuries associated with the spine.
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20
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WLADMIR VIRGILIO VERLY
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Microstructural characterization and evaluation of corrosion resistance of galvanized steel after folding
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Líder : IVETE PEIXOTO PINHEIRO SILVA
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MIEMBROS DE LA BANCA :
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IVETE PEIXOTO PINHEIRO SILVA
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MARCELLO ROSA DUMONT
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MÔNICA MARIA DE ABREU MENDONÇA SCHVARTZMAN
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PAULO RENATO PERDIGÃO DE PAIVA
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Data: 16-ago-2018
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The Light Steel Frame (LSF) is an alternative building system to the traditional building system using reinforced concrete, where prefabricated galvanized steel sheets are used for construction of houses and small buildings. The steel sheets used in this process undergo through mechanical forming processes, as folding, to acquire the needed format for assembling the structures. The corrosion behavior of galvanized sheets, however, can vary according to modulus of deformation that the part has suffered, that is, different regions of same part can presents a different corrosion behavior. This study has as objective evaluate the corrosion resistance of galvanized steel sheet after forming by folding in comparison with the corrosion resistance presented by non-folding samples. To carry out this work, was analyzed 25 galvanized steel samples used to build the metallic structure of LSF construction system. The samples were previously characterized by measuring the thickness of coating and microstructural analysis of coating. The samples were separated in five groups, where one group didn’t suffered forming and, on other groups, the samples were folded forming angles of 30°, 60°, 90° and 120°. After that, all the samples, including non-folded, were submitted to corrosion test using a galvanostatic / potenciostatic. The corrosion analysis were carried out by comparing the corrosion potential Ecorr showed by the samples in different forming situations. The results has showed that folded samples has presented higher corrosion potential than non-folded samples, confirming the hypothesis that mechanical forming influences on the corrosion resistance of material. Also, the results has showed that the percentage of deformation suffered by the coating have influence on the acceleration of corrosion process.
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21
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CLAUDINEI MARGARIDA DE MORAIS
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Study of the dispersion of functionalized ZnO nanoparticles in autocalytic chemical nickel fine films
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Líder : CLAUDINEI REZENDE CALADO
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MIEMBROS DE LA BANCA :
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CLAUDINEI REZENDE CALADO
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CLEVERSON FERNANDO GARCIA
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SIDNEY NICODEMOS DA SILVA
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Data: 17-ago-2018
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The existence of materials that achieve very specific properties that serve increasingly sophisticated activities for the industry causes research in materials such as specialized coatings such as nanomaterials to be demanded. Nanoscience has developed and disseminated its use. The industries have turned to nanotechnology to give technical viability to several increasingly complex projects. Of course, surface coatings also accompanied this demand. In this work, studies were done to synthesize the nickel-phosphorus (Ni-P) coating and to insert nanoparticles of functionalized zinc oxide in the medium. The bath parameters that directly influence the coating characteristics such as temperature, pH, surfactant type and concentration as well as the concentration of the nanoparticle itself were tested. After obtaining the desired coatings, X-ray diffraction analyzes were performed to prove the formation of this coating having a thickness of approximately 15 micrometers. In the scanning electron microscope with an increase of up to 3500 times the transversal sections of this coating were observed to verify the uniformity, thickness and the incorporation of these nanoparticles. A qualitative technique for corrosion resistance based on ASTM G48 was applied to the overcoating while the surface hydrophobicity of the samples was measured in the BET. The results of this work indicated that the Ni-P metal binary synthesis was obtained and the functionalized zinc oxide nanoparticles were incorporated into it. It was also shown that the hydrophobicity of the surface coated with the zinc oxide functionalized was increased by about 45% relative to the AISI 1020 steel substrate. The corrosion resistance was also increased with the addition of the nanoparticles.
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22
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Gabriela Leite Mota
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Corrosion analysis of UNS S31803 duplex steel after forming and welding processes
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Líder : IVETE PEIXOTO PINHEIRO SILVA
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MIEMBROS DE LA BANCA :
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IVETE PEIXOTO PINHEIRO SILVA
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MARCELLO ROSA DUMONT
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SIDNEY NICODEMOS DA SILVA
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WELLINGTON LOPES
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Data: 29-ago-2018
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This study is an integral part of a broader project aimed at the construction of a hydrocyclone for the removal of high levels of oil in water in order to allow the replacement of gravitational separators on offshore platforms. The materials selected for application in this industry must be of high mechanical and corrosive strength due to the complex processing characteristics. The stainless steel duplex UNS S31803 is a commercial steel, which has been widely used for such applications. In this work, the objective is to evaluate the effect of the conformation and welding processes, in the microstructure and corrosion resistance of the material. The plates duplex steel UNS S31803, 1,8mm, were ceded by Aperam South America. The sheets were cold conformed by folding at a 90 ° angle. After the folding, the pieces received a weld bead by simple deposition by the TIG -Tungsten Inert Gas welding process, with a thermal input of 0,4 kJ/mm2, realized in the ESAB. For the analysis of the material in the three studied conditions, material as received (MR), shaped material (MC) and shaped and welded material (MS), characterization tests were performed (MO/MEV), X-ray diffraction, volumetric analysis of the ferritic phase with the aid of a ferritecope and by image analysis by ImageJ®. For analysis of the corrosive properties, cyclic potentiodynamic polarization tests were applied to the material under the three conditions studied. The results showed that only in the conformed material, there were indications of phase transformations induced by cold deformation (γ → α'). For the deformed and welded material, the volumetric fraction of ferrite in the heat-affected zone increased significantly. No formation of the sigma phase was observed, but there was precipitation of chromium nitrides in the ferrite due to the high cooling rate after welding. In the cyclic polarization tests, it was found that the welding conditions imposed on the material, after the conformation, impaired its performance in terms of its corrosion resistance, affecting the regeneration of the passive film.
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23
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Silvio Luiz Francisco Osorio
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Evaluation of the mechanical and thermal performance of epoxy resin reinforced with carbon nanotubes and graphene for aeronautical use
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Líder : CLAUDINEI REZENDE CALADO
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MIEMBROS DE LA BANCA :
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CLAUDINEI REZENDE CALADO
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SIDNEY NICODEMOS DA SILVA
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CLEVERSON FERNANDO GARCIA
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Data: 31-ago-2018
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The present research investigates the mechanical performance and the thermal conductivity of epoxy resin matrixloaded with carbon nanotubes and graphene for application with carbon fibers on aircrafts components, manufactured on composite materials. The epoxy resin currently usedpresentshigh fragility and low tenacity to fracture, both are typical conditions to appearance of micro-cracks, oncepropagatedcanprovokeput in thecompositestructuralstability in risk. In addition, epoxyresinshavenotgood thermaland electrical conductivity.On the other hand, the nanomaterials,as carbon nanotubes and graphene, have a very high mechanical resistance, flexibility and hightenacity to fracture when folded or twisted, and also, they have high thermal and electrical conductivity.In this sense, samples of epoxy resin with the insertion of different concentrations of carbon nanotubes and graphene (between 0,1 and 0,5 % of mass) were prepared.The nanocomposite combinations obtainedweresubmmitedtomechanicaltestsandphisical/chemicalanalysis, in ordertodeterminatethecombinationwhichprovidethebestmechanicaland termal performance, incomparisontothepureresin. The first results of tension and bending tests corroborated with our expectations. There was a significant increase in the mechanical properties of the resin reinforced with carbon nanotubes and graphene, compared to the pure epoxy resin.The combination which provided better result was the epoxy resin with addition of 0,5% in mass of graphene. In this particular condition, the limit of resistance to tension and tenacity of the material increased 120% and 150%, respectively. Another important and significant result was the increase of 400% in the thermal conductivity, achieved by combination with only 0,1% of graphene. So, the data obtained experimentally indicatedthatinsertionofdeterminatedquantitiesofnanomaterials (in special graphene) tothepolimer matrizprovides superior mechanicaland termal characteristicstofinalnanocomposite. Asconclusion, thenanocompositesfound in thisresearchpresent high potencial for replacingpureepoxyresinonaeronautical componentes, as wingandfuselage, whichcouldbeeven more resistantandlighter.
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24
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VICTOR SOUZA ESTEVES LIMA
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NITRETATION BY ELECTRICAL DISCHARGES OF AISI 4340 STEEL UNIFORMIZING THE NITRATE LAYER
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Líder : ERNANE RODRIGUES DA SILVA
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MIEMBROS DE LA BANCA :
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ERNANE RODRIGUES DA SILVA
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MARIA CELESTE MONTEIRO DE SOUZA COSTA
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ROGERIO FELICIO DOS SANTOS
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Data: 28-sep-2018
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The industrial sector seeks in all its processes ways to optimize the production of mechanical components, seeking still improvements in the physical and mechanical properties of the materials. EDM is a process that has been studied because it allows some superficial modifications to be produced, at the same time as the part is machined. Previous studies have demonstrated the feasibility of machining metallic materials by EDM, immersed in aqueous solution containing urea, obtaining a surface enriched with nitrides which increases the hardness of the part, but none showed uniformity of the machined layer. In this work, the feasibility of nitriding samples of AISI 4340 steel by the EDM process by penetration using dielectric fluid as deionized water and urea was studied. As electrode tool were used graphite and electrolytic copper. The operating parameters of the EDM machine were adjusted in such a way as to allow the formation, dissipation of a plasma channel and maintenance of the uniform surface layer. The influence of the tool electrode on the machining performance, the microstructure and the uniformity of the nitrided layer were analyzed through material removal rate (TDM), wear rate (TD) and relative volumetric wear (DVR), microscopy as well as an X-ray diffraction analysis to prove the formation of nitrides on the machined surface. The analyzed images confirmed the formation of the rectified and nitrided layers. The roughness of the samples after machining and in the successive polishing steps were evaluated where 10μm thicknesses were obtained in the machined surface. There is a decrease in the concentration of nitrogen from the surface. It was performed microhardness where it was verified that there was gain in the hardness. By means of these analyzes it can be concluded that the copper electrode presented in the sample a greater uniformity thus allowing the removal of the recast layer.
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25
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IGOR PAIVA WAKABAYASHI
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Evaluation of the thermal and mechanical properties of the fiber steel reinforced concrete
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Líder : WEBER GUADAGNIN MORAVIA
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MIEMBROS DE LA BANCA :
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AUGUSTO CESAR DA SILVA BEZERRA
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CRISTINA ALMEIDA MAGALHÃES
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WEBER GUADAGNIN MORAVIA
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Data: 30-oct-2018
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The need to improve the concrete characteristics in the civil construction structures provided the elaboration of concrete with additions of fibers. The addition of metallic fibers in the cementitious matrix is associated with the mechanical strength gain and the cracking control of the concrete. This research evaluated the characteristics of reinforced concrete by steel fibers and analyzed the influence of metallic fibers on their mechanical performance and thermal properties. In this study, 20kg / m³, 40kg / m³ and 80kg / m³ of metal fibers were selected for comparison with the reference concrete, without the presence of fibers. As a result, the application of the fibers in a situation of resistance to simple compression showed appreciable results only in the situation of higher fiber concentration, different from the flexural tensile stress where the increase of the fiber concentration showed increase in the maximum tension, and the capacity post-cracking of concrete, tenacity numerically relates this difference. The thermal conductivity increases with the presence of fibers, but the amount of fibers does not directly influence this result. The thermal expansion of the fibrous and reference concrete are equivalent up to 65 ° C, with increasing temperature and evaporation of the water the addition of fibers assists in the physical stability of the material, in which case the expansion was greater than the reference. With the increase of the fiber content the cementitious matrix will present less free water in the interstices, this is observed with the help of scanning electron microscopy and its influence verified through the whole work.
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26
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Luísa Arantes Fernandes Vieira
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Mitigation of carbon dioxide by adsorption process
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Líder : IVETE PEIXOTO PINHEIRO SILVA
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MIEMBROS DE LA BANCA :
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IVETE PEIXOTO PINHEIRO SILVA
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PAULO RENATO PERDIGÃO DE PAIVA
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SIDNEY NICODEMOS DA SILVA
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CAMILA SOARES FONSECA
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Data: 31-oct-2018
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One of the biggest environmental challenges today is reducing the emission of carbon dioxide (CO2) into the atmosphere. It is one of the greenhouse gases, being generated mainly through the burning of fossil fuels. Its capture has been the subject of countless researches and new technologies, as well as distillation, gas / solid reaction, adsorption, etc. This work proposes the production and study of the adsorptive characteristics of the hydroxyapatite (HAP) synthesized using as the calcium source chicken eggshells. Hydroxyapatite is not widely used as a gas adsorbent and is nowadays its main application in the biomedical sector due to the similarity with the mineral phase of human bones. The chicken eggshell, being a calcium carbonate-rich waste and of no commercial value, appears as a source of calcium carbonate for the synthesis of HAP. For the preparation of the eggshell, hygiene was initially carried out for removal of organic material and some unwanted impurities in the process. The eggshell was submitted to the Thermogravimetry (TG) test where the ideal decarbonation temperature was determined: 805ºC. Calcination of the shell for conversion to calcium oxide was carried out using muffle type alumina crucibles. The result of the X-ray Diffraction (XRD) test for the egg shell after calcination was satisfactory. The synthesis reaction generated a compound with some crystals of hydroxyapatite and calcium hydroxide. After calcining the compound was reexamined by XRD and the result was also satisfactory, being found peaks confirming the presence of hydroxyapatite. The adsorption tests were carried out with carbon dioxide at levels compatible with those found in industrial chimneys, where there is the burning of fossil fuels. Quantifications of the initial levels of CO2(14 ± 1%) were made with adsorption evaluation in cycles of up to 180 minutes at room temperature. The tests were made by varying the mitigating material in calcined and non-calcined, and in environments with or without light. Comparison of the adsorption results of the calcined HAP and non-calcinedHAP showed a higher efficiency of the non-calcined HAP in the light environment. In this scenario there was adsorption of approximately 44g of carbon dioxide to each gram of mitigating material.
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27
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Giovanni Helbert Quaresma
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Improvement of performance of porcelain electrical insulators through the use of hydrophobic polymeric coatings
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Líder : CLAUDINEI REZENDE CALADO
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MIEMBROS DE LA BANCA :
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CLAUDINEI REZENDE CALADO
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SIDNEY NICODEMOS DA SILVA
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CLEVERSON FERNANDO GARCIA
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Data: 31-oct-2018
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The dielectric properties and mechanical strength of ceramic porcelain insulators are fundamental to guarantee to the electrical system, acceptable rates of continuity in the supply of energy through transmission lines and electric distribution networks. However, atmospheric conditions and the amount of pollutants present therein can severely compromise the efficiency of the operation of said insulators. This situation is due to the fact that they have surfaces composed of metallic oxides that have high wettability, especially when exposed to humid conditions such as mist, dew and rain. This characteristic can cause the formation of water film which, if continuous throughout the surface of the insulator, is capable of conducting electric current and closing an arc (a phenomenon known as flashover). In the present work, in order to improve the hydrophobicity of the surface of such insulators, the deposition of polymers was carried out on porcelain substrates used as electrical insulators through the use of drip and airbrush techniques. Measurements of contact angle between surfaces and water were performed using a goniometer to characterize the behavior of the used coatings. In order to evaluate the performance of the various coatings, specimens with ceramic enamel coating were included for comparison purposes only. The three coatings that presented the most promising results in terms of hydrophobicity were EPS (Expanded Polystyrene) + THF, EPS + Toluene and EPS + Chloroform applied through an airbrush. The EPS + Chloroform coating had a mean contact angle of 109.63 °, 3.6% higher than EPS + THF and 14.5% higher than EPS + Toluene. The ceramic enamel coating, as expected, presented hydrophilic behavior. In this way, the data obtained experimentally reveal that the EPS presents a great potential of application as an alternative to the materials already used in the market, because it is a reuse material, totally recyclable and economically viable.
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28
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Lucas Xavier Soares de Souza
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Preparation of aluminum foams: evaluation of the influence of the granulometry of the base metal powders, the compacting pressure and the soaking time of the heat treatment
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Líder : IVETE PEIXOTO PINHEIRO SILVA
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MIEMBROS DE LA BANCA :
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IVETE PEIXOTO PINHEIRO SILVA
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PAULO RENATO PERDIGÃO DE PAIVA
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ALMIR GONCALVES VIEIRA
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Data: 01-nov-2018
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In the context of energy efficiency in the transport area as in the automobile and aeronautical industries, the reduction of weight in structures plays an important role.
As an alternative to this, metallic foams, more specifically aluminum foams, come with great potential for application and, in addition to benefiting from fuel consumption, can contribute to safety and comfort in cars and aircraft. This is primarily due to the properties of aluminum which, in combination with the foam structure, can enhance the properties of this element for particular applications. The goal of this work was to obtain aluminum foam from powders by the pulverotechnology route and to evaluate the production conditions such as geometry and particle size of aluminum powders, compaction pressure and time of heat treatment. For the present work, the titanium hydride was used as blowing agent and pure aluminum was used for the base metal. The pulverotechnology was the route to obtain the foam, with cold uniaxial pressing in rigid matrix as compacting method. Aluminum foams, with relative density of 69 to 95% of the value of the aluminum density used, were obtained. After analysis of compaction curves, it was verified that the granulometry and geometry of the powders used are characteristics that must be evaluated to define the best compression pressure. This, in turn, has shown that it plays a decisive role in the formation of aluminum foams, since in addition to imprisoning the blowing agent powders between the powders of the base metal the pressure must also be enough to break the oxide layer present in the aluminum powders. The heat treatment time directly interfered in the foam quality. Long heat treatment times may benefit pore coalescence and foam collapse with the formation of preferred pathways for the escape of gases formed by the decomposition of the blowing agent. The best results obtained in this work were for aluminum type 1, compression pressure 500MPa and heat treatment time of 10 minutes at a temperature of 710 ° C.
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29
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WEBER DE ALMEIDA LIMA
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Cold cracking in GMAW welding of a high strength steel
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Líder : MARIA CELESTE MONTEIRO DE SOUZA COSTA
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MIEMBROS DE LA BANCA :
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ERNANE RODRIGUES DA SILVA
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MARIA CELESTE MONTEIRO DE SOUZA COSTA
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ROGERIO FELICIO DOS SANTOS
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Data: 09-nov-2018
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The fabrication and development of high strength structural steels has advanced in the last decades, being used to obtain the thermomechanical controlled process - TMCP, which provides gains of mechanical resistance and tenacity by obtaining a homogeneous microstructure of fine-grained, resulting in components, with good formability and weldability. In view of these advances that allow the entry of new materials in the market, the study of the discontinuities that are subject to welded joints is necessary, among them the cold cracking, known as hydrogen cracking. For the study of this work a high strength structural steel was used, and it was submitted to the Tekken Test (Y-Groove) welding test by the Gas Metal Arc Welding - GMAW process. The overall objective of the work was to verify the occurrence of cracks in the regions of the weld, observing the type of microstructure resulting and factors that provided the same. The results showed the effect of the preheating in the welded samples, resulting in mechanical and microstructural changes, being the region of coarse-grained of the heat-affected zone that presented the significant results regarding the cracking by hydrogen.
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30
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BARTIRA RODRIGUES NEVES
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Study of the performance of hot recycled asphalt mixtures with 100% of reclaimed asphalt pavement for cold application in pavement maintenance
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Líder : FLAVIO RENATO DE GOES PADULA
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MIEMBROS DE LA BANCA :
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FLAVIO RENATO DE GOES PADULA
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IVETE PEIXOTO PINHEIRO SILVA
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CLAUDIO JOSE MARTINS
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Data: 19-nov-2018
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Resumen Espectáculo
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The hot recycling of Reclaimed Asphalt Pavement (RAP), as material to compose asphalt mixtures, aims to reinforce the sustainability concept of the asphalt paving area, promoting the mitigation of damages caused by oil and natural aggregates extraction. RAP is a residue, which is produced in abundance during the maintenance of asphalt paving, but it is still little used in hot asphalt recycling mixtures. The main objective of this research was to study the performance of hot recycled asphalt mixtures with 100% of RAP, for cold application in pothole. In the experimental research, before the materials dosages, the physical characterization of RAP was carried out. The results of granulometry and bitumen extraction tests carried out for the RAP were approved for use in the asphalt mixture dosages, since they presented the characteristics established by the reference curve of DNIT ("C" range). The addition of Re-refined Engine Oil Bottom (REOB) in the hot recycled asphalt mixtures had as function to maintain the workability of the mixture at ambient temperature and provide rejuvenation of the properties of the aged binder present in the RAP. The mechanical characterization was made with compressed samples, which were molded by the Marshall methodology, to perform the tests of diametral compression strain and Marshall stability and fluency. The results obtained in this work confirmed the research proposal, which were presenting dosages of hot recycled asphalt mixtures with 100% of RAP and addition of REOB, petroleum asphalt cement (bitumen), rubber powder and lime, with good workability and mechanical strength. The developed mixtures characterized as an alternative material in pothole maintenance, with cold application.
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31
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ANA FLÁVIA RODRIGUES SALES
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Processing, characterization and evaluation of biocompatibility of PLGA and Collagen blends for controlled release of Rosmarinic Acid
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Líder : SIDNEY NICODEMOS DA SILVA
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MIEMBROS DE LA BANCA :
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SIDNEY NICODEMOS DA SILVA
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IVETE PEIXOTO PINHEIRO SILVA
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VIVIANE GOMES DA COSTA
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Data: 23-nov-2018
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Resumen Espectáculo
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Intraocular implants have been studied with the aim of improving the treatment of ophthalmological diseases related to neovascularization. One of the drugs whose antiangiogenic function has been recently studied is Rosmarinic Acid (RA). In this work, blends were produced with 50% PLGA - poly (lactic - co - glycolic acid) 75/25 and 50% Collagen type I and 75% PLGA 75/25 and 25% Collagen type I - for evaluation of degradation (pH 7.4 and 37 ° C) simulating the release of AR into the vitreous ocular. Implants with different degradation rates were found, evidencing that the blending is promising for the controlled release of drugs. For the characterization of the raw material, as well as the blends with and without the drug, the X-Ray Diffraction (XRD), X-ray Spectroscopy with Dispersive Energy (EDX), Scanning Electron Microscopy (SEM), Thermogravimetry (TG), Fourier Transform Spectroscopy (FTIR) and contact angle measurement. In addition, hemocompatibility tests, cell viability of the implants were performed by the MTT (tetrazoline salt) reduction method, as well as the test of reactive oxygen species (ROS) in the blends with and without the drug. The formed blends have no chemical interaction and therefore the product of the degradation thereof is composed of the sum of the products of their raw materials, already known. In addition, the blends present potential of application as biomaterials for controlled release of anti-VEGF by the tests performed, since they are not hemolytic, besides having good cellular viability and ROS reduction.
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32
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Cristina Aparecida Esteves
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Production and characterization of aluminum foams
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Líder : SIDNEY NICODEMOS DA SILVA
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MIEMBROS DE LA BANCA :
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SIDNEY NICODEMOS DA SILVA
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IVETE PEIXOTO PINHEIRO SILVA
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SANDRO CARDOSO SANTOS
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MICHELLE CRISTIANE DA SILVA DUARTE
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Data: 27-nov-2018
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Resumen Espectáculo
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The literature shows that aluminum foams have a wide range of applications as structural material mainly in the aeronautical and automotive industries due to the physical properties of thermal and acoustic insulation, as well as the ability to absorb mechanical stresses of compression and / or torsion, among other characteristics such: weight reduction and energy saving. This work aims to contribute to the studies related to parameters to obtain aluminum foams via the route of powder metallurgy using the cold conformation mechanical compaction. A drawn SAE 1045 steel mold was machined and heat treated (quenching and tempering) in the quest for surface hardening required to withstand the high loads used in the uniaxial compression of the powders (aluminum and titanium hydride) used in the proposed experiments matrix. The raw materials consisted of aluminum powder (Al), powdered titanium hydride (TiH2) as foaming agent and zinc stearate as the release agent. Fifteen green test specimens, divided into 5 batches, denominated A, B, C, D and E, with expander concentration 0.00%, 0.80%, 1.00%, 1.20% and 1.50% respectively. A priori, compaction occurred at a pressure of 350 MPa, after the green CPs were sintered at a heating rate of 16 ° C / min to the temperature of 710 ° C in an inert atmosphere, argon, remaining at this temperature for 8 minutes. The physicochemical characterization of materials and CPs were used to determine the particle size, the Thermogravimetric Analysis (DTG) specifically for titanium hydride, in order to verify the release temperatures of X-Ray Diffraction (XRD) for the verification of crystalline structure, X-ray Fluorescence Spectroscopy (EDX) for analysis of chemical composition, and finally Scanning Electron Microscopy (SEM) for analysis of surface morphology proof bodies. The following foaming processing parameters and the mold have proven to be effective. The materials produced presented values of relative densities between 0.44 and 0.73, with the volume increasing up to 126%, for the studied parameters of compaction with 350MPa, heat treatment 710ºC / 8 min in inert atmosphere.
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33
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RAFAELA NEPOMUCENO E VIDIGAL
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Influence of the initial state and the processing parameters on the microstructure and mechanical behavior of a steel assisted by the TRIP effect after diverse thermal processes
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Líder : ELAINE CARBALLO SIQUEIRA CORREA
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MIEMBROS DE LA BANCA :
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CLAUDIO TURANI VAZ
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ELAINE CARBALLO SIQUEIRA CORREA
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MARIA TERESA PAULINO AGUILAR
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WELLINGTON LOPES
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Data: 06-dic-2018
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Resumen Espectáculo
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The quest for advances in environmental preservation and safety has led the automotive industry to research solutions that combine higher engine efficiency, better aerodynamics and reduced vehicle weight. In this context, TRIP steels stand out because they offer high mechanical strength and good formability, thus providing the use of thinner sheets with higher mechanical strength. The main characteristic of TRIP steels is the phenomenon of plasticity induced by phase transformation, as a consequence of the transformation of austenite retained in martensite during deformation. However, only the effects of martensitic transformation do not guarantee the mechanical properties of TRIP steels. It is a set of factors, for example the presence of several phases influences directly on the mechanical properties due to the hardening processes. Therefore, it becomes complex to establish direct relations of the phases with the mechanical properties. The objective of this work was to analyze the effects of heat treatment parameters on the microstructure and mechanical properties of a TRIP steel, through a microstructural and mechanical characterization. Analysis were conducted in terms of optical microscopy, scanning electron microscopy, X-ray diffraction, hardness tests, tensile tests and analyzes concerning the work hardening behavior of the material by different methods. In conclusion, it was observed that the microstructure and the mechanical properties were more influenced by the effects of austempering time and the initial microstructure. In addition, it was observed that the conditions with martensitic initial structure austempered at 400ºC, in general, presented better performance, since they correspond to the conditions with retained austenite more stable and with greatest gain of mechanical properties.
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34
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Guilherme Ramos Righi
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Effects of Welding and Stress Relief Heat Treatment on the Machinability of Austeniti Stainless Steel
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Líder : SANDRO CARDOSO SANTOS
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MIEMBROS DE LA BANCA :
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ERNANE RODRIGUES DA SILVA
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SANDRO CARDOSO SANTOS
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WAGNER SADE
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JOSÉ RUBENS GONÇALVES CARNEIRO
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Data: 14-dic-2018
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Resumen Espectáculo
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Field machining is an operation applied to parts that have passed through different processes during their manufacture as mechanical forming, welding and heat treatment, so that the machinability of parts made from austenitic stainless steel – material widely submitted to this operation – can be modified (impaired) by changes in the material microstructure, amending certain properties. Therefore, this work involves the evaluation of the influence of welding processes and stress relief heat treatment – typical manufacturing processes – on the machinability of AISI 304 austenitic stainless steel, a material with satisfactory corrosion resistance and weldability and that has broad applications in the industry.It was observed the behavior of the parent metal (PM) and heat affected zone (HAZ) regions of the AISI 304 austenitic stainless steel bars by manual TIG process and subsequently heat treated for partial stress relief at a temperature of 350°C for 30 minutes, in addition to analysis of the parent metal region of a as received material bar used to reference. For this analysis, dry and cutting fluid drilling machinability tests were performed with constant pressure and was applied by measuring the drilling time in a path of 20mm, as well as Vickers microhardness tests and metallographic analysis to evaluate the microstructural transformations.The results showed that in the condition as welded and thermally treated, the material showed better machinability in the PM and HAZ regions when the cutting fluid was applied. In the same processing conditions, the machinability in the HAZ is lower than in the PM region independent of the use of cutting fluid, and such result is caused by the occurrence of hardness increase in the HAZ, evidenced by austenitic grain refining. Therefore, the results allow concluding that the constant pressure drilling machinability test is an effective method for analyzing the machinability of the processed and as received AISI 304 such that this material had its lowest machinability in the HAZ under the condition of being processed and dry tested.
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35
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Soraia Sandra Pires
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Aspectos tribológicos de um revestimento de carbono tipo diamante sobre uma planta de aço rápido AISI M2
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Líder : ERNANE RODRIGUES DA SILVA
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MIEMBROS DE LA BANCA :
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ERNANE RODRIGUES DA SILVA
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IVETE PEIXOTO PINHEIRO SILVA
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PAULO SÉRGIO MARTINS
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RONEY AMARANTE BRAGA
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Data: 21-dic-2018
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Resumen Espectáculo
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The amorphous carbon coatings, known as Diamond-like Carbon (DLC) are thin films formed by different proportions of carbon`s bonds sp2 (graphite) and sp3 (diamond) and have special characteristics as high hardness and chemical inertia. Its application looks for the effective improvement of the chemicals, physicals and mechanicals proprieties of the bulks metals used as substrate and protection to abrasive and adhesive wear of the base metal. The DLC film’s application are large, highlighting the use in gears, medical instruments, hydraulic systems and cutting tools. Widely used in high-speed steel drills, to non-ferrous metals machining, for example, to processes of drilling blocks of aluminum-silicon alloys (Al-Si) in the automotive industry. The present work studies the tribological behavior of the tetrahedral hydrogen- free DLC coating deposited by plasma assisted PVD method by cathodic arc in vacuum. It investigates the influence of the high-speed steel AISI M2 substrate roughness in the adhesion, thickness, abrasive wear resistance and friction resistance against an aluminum-7,76%silicon alloy. The specific wear rate of the coating was bigger in the finish gross substrate. However, was verified that the abrasive wear is not proportional to roughness. The low adhesion of the finish ground substrate was not a determinant factor to influence the abrasive wear. The thickness of the coating, calculated by the craters diameters was different of the real thickness obtained by SEM. In the pin on disk test, the DLC against Al-Si presented a medium friction coefficient of 0,374, being 20% smaller related to AISI M2 steel/Al-Si. The friction coefficient did not have a proportional relation with the roughness. The more roughness substrate presented the smaller friction coefficient during the pin on disk test.
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