Navegando por Autor "Gurgel, Diego Pires"
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Artigo Development of a microwave absorbing material based on molybdenum-doped niobium pentoxide(Scielo, 2019-01) Mashhadikarimi, Meysam; Gurgel, Diego Pires; Queiroz Júnior, Idalmir de Souza; Silva Júnior, M. Q. da; Andrade, H. D. de; Gomes, Uílame UmbelinoThis work aimed to perform the characterization of electrical properties of niobium pentoxide, Nb2O5, pure and doped with molybdenum, prepared by powder metallurgy route and to do a comparative analysis of the influence of this material when sintered in a muffle or in a microwave oven. The results showed that the doping of the niobium pentoxide with 0.5% or 1% of molybdenum along with the process of sintering in a microwave oven make the material more applicable as a microwave absorber material for electromagnetic radiation in the UHF (ultra-high frequency) range between 0.3 to 3 GHz. The motivation of this work was associated with the fact that in Brazil are located two of the largest niobium reserves in the world. Under this view, the study of the processing of the ceramic materials is important considering possible technological applicationsArtigo Development of a novel triple-layer polycrystalline diamond compact(Elsevier, 2021-01) Mashhadikarimi, Meysam; Medeiros, Regina Bertília Dantas de; Barreto, Lucas Pires de Paiva; Gurgel, Diego Pires; Gomes, Uílame Umbelino; Filgueira, MarcelloThe objective of this research was to obtain a triple layer Polycrystalline Diamond Compact (PDC) via the High-pressure High-temperature (HPHT) sintering method. A thin layer of WC with 20 wt.% Nb/Ni was used as an interface between the top layer of Polycrystalline Diamond (PCD) with pure Nb binder and WC 10 wt.% Co substrate. Sintering was performed at 1750 °C under 7.7 GPa of pressure. Microhardness variation was measured and microstructural/structural studies were done via SEM/EDS and XRD. The overall results showed that this new kind of PDC can be produced successfully using pure niobium as a binder for the PDC layer and no sign of graphitization was detected. It was also found that using an interface having the resemblance to both substrate and sintered diamond body caused good adhesion between layers that can potentially enhance performance and durability of PDCTCC Efeito de concentração de SIC no comportamento de sinterização e propriedade mecânica de compósito AL/SIC(Universidade Federal do Rio Grande do Norte, 2021-04-27) Silva, Edna Gomes da; Mashhadikarimi, Meysam; Peres, Maurício Mhirdaui; Gurgel, Diego PiresOs Compósitos de matriz metálica reforçados com SiC são muito utilizados devido excelentes combinações de propriedades, tais como alta dureza e alta condutividade térmica, resistencia ao desgaste e à corrosão. O compósito de matriz de alumínio, principalmente reforçado com carbeto de silício, é utilizado em diversos setores indústriais, principalmente no automobilístico e na aviação, substituindo as ligas ferrosas. Este trabalho tem como objetivo estudar o efeito de concentração de SiC no comportamento de sinterização e propriedade mecânica de compósito Al/SiC. Os pós utilizadas foram moídos e misturados com teores de 5%, 10% e 15% em peso de Carbeto de Silício em um moinho do tipo planetário, com uma rotação de 300rpm durante 1h . Os pós foram então compactados sob uma pressão de 200Mpa e 400Mpa e sinterizados a 570ºc por 1h. Em seguida as amostras foram analisadas por Microscopia Eletrônica de Varredura, Fluorescência de Raios-X e dureza. Como resultado observou-se a incorporação das partículas duras, que ficaram bem dispersas no Al com distribuição uniforme. O efeito do silício diminuiu o tamanho das partículas do Al. A densidade do material em 5% e 10% aumentou com a pressão de compactação, porém em 15% de SiC a densidade diminuiu, pois maior porcentagem de SiC indicou uma baixa densificação do material analisado. A dureza do compósito analisado aumentou com adição de SiC, onde maior a adição de partículas duras, maior a dureza e maior a porosidade do compósito analisado.Artigo Niobium as a new binder for polycrystalline diamond (PCD) sintered via High Pressure-High Temperature (HPHT)(Elsevier, 2020-08) Mashhadikarimi, Meysam; Gurgel, Diego Pires; Rodrigues, Mayara Adrielly Leal de Oliveira; Barreto, Lucas Pires de Paiva; Filgueira, Marcello; Gomes, Uílame Umbelino; Bichler, LukasIn this research, the effect of adding 2.5, 5.0 and 10 wt% niobium (Nb) as a binding agent was investigated for High Pressure-High Temperature (HPHT) sintering of polycrystalline diamond (PCD). Samples were sintered at 1750 °C and 7.7 GPa. Detailed characterization of the as-sintered materials revealed a uniform dispersion of the Nb additives in the diamond matrix and no interfacial cracking was observed. Higher concentration of binder increased tendency to intergranular failure. The formation of NbC and NbC0.84 phases after sintering was identified, indicating that some of the matrix carbon may have undergone graphitizationArtigo Preparation and characterization of sintered polycrystalline diamond (PCD) with 15 wt% Nb binder(Elsevier, 2020-06) Mashhadikarimi, Meysam; Barreto, Lucas Pires de Paiva; Rodrigues, M. A. L. O.; Gurgel, Diego Pires; Gomes, Uílame Umbelino; Filgueira, Marcello; Medeiros, Regina Bertília Dantas deThis study aimed to obtain and characterize a polycrystalline diamond body (PCD) sintered with 15 wt% Nb binder, through the high-pressure high-temperature (HPHT) sintering techniques at three different temperatures of 1650 °C, 1750 °C, and 1850 °C, with a pressure of 7.7 GPa. Characterizations on the starting powders were performed before and after high energy ball milling, and then the obtained mixture was sintered. The results showed that niobium could perform as a good binder for the sintering PCD at the specified concentration, achieving relative densities in the range of 96% to 100% for all three sintering temperatures. Also, analyses of the electron micrographs and the Raman spectrograms showed that there was no graphitization, a common problem in this type of material, and there was uniform dispersion of the niobium at the interfaces of the diamond particles, and no cracking.