Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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Resultados da Pesquisa
Trabalho de Conclusão de Curso Propriedades mecânicas de componentes em peek produzidos por manufatura aditiva:(2024-06-24) Figueiredo, Pedro Rafael Della RiccoEste estudo investigou os efeitos do processo de recozimento no PEEK (poliéter-éter-cetona) produzido por manufatura aditiva FFF (Fabricação por Filamento Fundido). Os corpos de prova foram submetidos a análises de dimensões, difração de raios-X, calorimetria diferencial e ensaios de flexão. Os resultados revelaram que o recozimento não apenas alterou as dimensões dos corpos de prova, com uma redução na largura e espessura, mas também promoveu aumento na cristalinidade do material. A análise por difração de raios-X mostrou que as amostras recozidas apresentaram uma média de cristalinidade de 11%, enquanto as amostras não tratadas termicamente tinham uma média de 7%. Essa mudança estrutural resultou em um aumento da resistência e rigidez das amostras recozidas, com um limite de escoamento médio de 110 MPa e um módulo de elasticidade médio de 3,4 GPa, em comparação com 81 MPa e 2,4 GPa, respectivamente, para as amostras não tratadas termicamente. Apesar do recozimento realizado em moldes de gesso, ainda ocorreram alterações dimensionais nas amostras, mas sem distorções.Trabalho de Conclusão de Curso Avaliação das propriedades mecânicas de um aço dual-phase(2023) Morais, Amanda FalcariEste projeto teve por objetivo avaliar as propriedades mecânicas e microestrutura de um aço dual-phase produzido em laboratório, verificando seu desempenho para uma possível aplicação estrutural na indústria automobilística, para a qual se espera principalmente boas ductilidade e resistência mecânica. Através do ThermoCalc© foram objetivadas amostras com frações volumétricas de martensita de 32,8%, 40,0% e 51,1% considerando três temperaturas diferentes de austenitização parcial, 728°C, 745°C e 765°C. Foram realizados ensaios de tração, ferritoscopia, dureza, metalografia e Difração de Raios-X (DRX) nas amostras após o tratamento térmico, a fim de analisar as propriedades mecânicas. Foi verificado que o limite de resistência e limite de escoamento apresentaram maiores valores com o aumento de temperatura. A dureza das amostras, assim como os valores de limite de escoamento e resistência, aumentou na presença de maiores teores de martensita por ser uma fase mais dura e resistente. O módulo de elasticidade mostrou valores não muito condizentes com a teoria, descartando-se a possibilidade de influência da austenita retida, assim, sendo proposto uma mudança no método de determinação do módulo. O alongamento uniforme dimunui na presença de maior fração volumétrica de martensita enquanto o alongamento total se mantém praticamente constante, os quais sofrem influência da homogeneidade de distribuição da ferrita nas amostras. O aumento da estricção é justificado pelo maior teor de austenita retida na estrutura e refino do tamanho de grão da ferrita. A análise por DRX apresentou apenas picos de ferrita que, por sua vez, engloba a microestrutura martensítica, além de não evidenciar picos de austenita, indicando que a austenita retida, está presente provavelmente com tamanho diminuto entre as ripas de martensita. A ferritoscopia comprovou a presença de austenita retida com teores pequenos de 1,7%, 5,2% e 8,8%, crescente com a temperatura de tratamento, sendo influenciada pela composição química (principalmente o elemento carbono), que afeta diretamente as temperaturas de transformação martensíticas (Ms e Mf). Com o auxílio do ImageJ© foi notado que as frações volumétricas de martensita objetivadas (32,8%, 40,0% e 51,1%) não foram atingidas (64,9%, 85,1% e 92,3%) provavelmente porque o tempo no patamar isotérmico não foi suficiente para formação da fração de equilíbrio de ferrita.- Reusing Surlyn® Ionomer Scraps in LDPE Blends: Mechanical and Thermal Properties(2023-01-05) BARBOSA, M. F.; Adriana Martinelli Catelli Souza© 2023 Universidade Federal de Sao Carlos. All rights reserved.This study aimed to evaluate the possibility of reusing industrial scraps of Surlyn® ionomer by obtaining blends with Low-Density Polyethylene (LDPE). Blends of LDPE and Surlyn® scraps were obtained by extrusion with compositions ranging from 25 to 75 wt% of the ionomer. Their melt flow index (MFI), morphology (SEM), mechanical (tensile, flexural, impact tests) and thermal properties (DSC, TGA, HDT tests) were analyzed. The morphology of the blends presented two phases, indicating the immiscibility of phases. Surlyn® incorporation promoted a decrease in the degree of crystallinity of LDPE and a slight increase in the thermal decomposition temperature. In addition, Surlyn® decreased the decomposition rate of LDPE. However, the decrease in the degree of crystallinity did not affect the mechanical properties of the blends. Incorporating ionomer in LDPE promoted an increase in tensile and flexural strength, tensile and flexural modulus and strain at break. Impact strength decreased with increasing ionomer concentration.
- PA6/PA66/talc composite: Effect of reprocessing on the structure and properties(2022-04-05) DOMINGO, G. D.; SOUZA, A. M. C.In this study the effect of repeated injection molding cycles on the structure and properties of polyamide 6/polyamide 66/talc (PA6/PA66/talc - 35/35/30) composite was investigated for samples subjected to one, four, and seven processing cycles. Their morphology (scanning electron microscopy), structure (Fourier transform infrared spectroscopy), melt viscosity (melt flow index [MFI]), mechanical (tensile, flexural, impact, and fatigue tests), and thermal properties (differential scanning calorimetry and thermogravimetric analysis tests) were analyzed. The increase in MFI value and the decrease in the maximum decomposition temperature of PA6, observed by TG analysis, for samples subjected to seven processing cycles, indicated a possible reduction in molar mass of the PA6/PA66 matrix. These samples presented a decrease in degree of crystallinity of PA6 and PA66, which was more pronounced for PA6. The reprocessing of the composite did not present changes in the mechanical properties up to the fourth processing cycle, except for fatigue life which presented a 59% reduction. Samples subjected to seven processing cycles presented a decrease in tensile and flexural strength as well as in tensile and flexural modulus. Charpy impact strength of the samples did not significantly change upon reprocessing. The micrographs of the fatigue fractured surfaces indicated that the weak talc-matrix interaction and talc-matrix debonding became more evident with increasing processing cycles.
- Influence of MMT and PP-g-MA incorporation on the morphology and mechanical properties of PP/SEBS blends(2018-07-11) TORRECILAS, H. V.; COSTA, L. C.; Souza A. M. C. Adriana Souza© 2018 Author(s).Blends of PP/SEBS containing montmorillonite clay (MMT) was studied. Maleic anhydride grafted polypropylene (PP-g-MA) was added aiming interaction improvement between blend components and MMT. The blends were obtained using a co-rotational twin-screw extruder. Samples for tensile and impact tests were obtained by injection molding and were characterized by tensile and impact tests. The blend morphologies were characterized by scanning electron microscopy (SEM) and by transmission electron microscopy (TEM). PP/SEBS blends containing MMT presented an increase in Young Modulus and impact strength and a decrease in elongation at break. This behavior was greater in the presence of PP-g-MA. The presence of the PP-g-MA had attracted the organoclay to the matrix due to the interaction between the platelets and the maleic anhydride group. In this nanocomposite, it was observed the presence of MMT within PP matrix and a slight decrease of the dispersed phase diameter.
- ABS/HIPS blends obtained from WEEE: Influence of processing conditions and composition(2016) De Souza A.M.C.; Cucchiara M.G.; Ereio A.V.© 2016 Wiley Periodicals, Inc.The recycling of acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) from postconsumer electronic equipment housing was investigated. A preliminary study of shot size and particle size effects on the mechanical properties of ABS/HIPS (50/50) blends obtained directly via injection molding was conducted. Injection-molded specimens of ABS/HIPS blends, obtained at different compositions with or without previous extrusion, were subjected to mechanical, thermal, and morphological testing. Preliminary studies showed that a smaller particle size resulted in higher tensile and impact strength, regardless of the shot size used during injection molding. ABS/HIPS blends obtained using previous extrusion presented a slight increase in Young's modulus and a decrease in elongation at break and impact strength. The increase in glass-transition temperature related to the Polybutadiene (PB) phases of these blends indicated a possible increase in crosslinking structures during extrusion. In addition, these blends showed a coarse and heterogeneous morphology, suggesting that ABS did not completely mix with HIPS. Compared to processing conditions, the blend composition appeared to have a much stronger effect on the mechanical properties. The results obtained suggest the possibility of obtaining ABS/HIPS blends directly via injection molding as long as small ground particles are used.
- Effect of Niobium on Phase Transformations, Mechanical Properties and Corrosion of Supermartensitic Stainless Steel(2017) de Oliveira M.P.; Calderon-Hernandez J.W.; Magnabosco R.; Hincapie-Ladino D.; Alonso-Falleiros N.© 2017, ASM International.The influence of niobium addition in a supermartensitic stainless steel with 13Cr-5Ni-2Mo has been studied. The steel with Nb tempered at 600 °C for 2 h showed improved mechanical resistance properties and lower degree of sensitization, without compromising elongation and pitting corrosion resistance, when compared to the reference steel. In order to understand the Nb effect in such steel, mainly regarding phase transformation, different tempering time intervals have been studied. The better performance of the SM2MoNb is attributed to the hindering effect that Nb has in the kinetics of the phase transformations during tempering, delaying the precipitation start and coarsening stages of the present phases.