Navegando por Autor "Filgueira, Marcello"

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    Effect of high-energy milling and sintering temperature on the structure of a hardmetal.
    (2018) Batista, Adriano Corrêa; Oliveira, Hellen Cristine Prata de; Filgueira, Marcello; Pinto, Maria Aparecida; Faria, Geraldo Lúcio de; Perpétuo, Genivaldo Julio
    This paper evaluated the effect of high-energy milling and sintering temperature on the structural characteristics of WC- 10%Co. These samples were sintered at temperatures of 1350°C, 1400°C and 1450°C. The cooling rate of 100°C/h was used within the temperature range of 1000°C and 800°C to relieve residual stress from the sintering process. The samples were submitted to X-ray diffraction analysis with Rietveld refinement in order to characterize, at the atomic level, the effects of each processing stage on the material structure. The high-energy milling process may have accelerated the dissolution process of a large part of the WC particles during sintering, contributing to the formation of n phases. The characterization techniques were effective to evaluate the effects of high-energy milling, sintering temperature and residual stress on the structural characteristics of the composites investigated and the formation of amounts above 34% by weight of the Co W C and Co W C phases.
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    Study of the abrasion resistance of Fe-Cu-Nb and NEXT 100® metallic matrices for the manufacture of diamond tools.
    (2018) Oliveira, Hellen Cristine Prata de; Assis, Paulo Santos; Leal, Thales Eduardo; Filgueira, Marcello; Batista, Adriano Corrêa; Perpétuo, Genivaldo Julio; Reis, Ana Carolina Fernandes
    The substitution of cobalt, present in the commercial binder metal matrix commonly used by the industry, was analyzed: 25,2%Fe-49,5%Cu-24,1%Co – NEXT 100® by the niobium element of the Fe-Cu-Co system, obtaining 4 metal matrices: 28,34%Fe–56,66%Cu–15%Nb; 25%Fe– 50%Cu–25%Nb; 21,67%Fe–43,33%C–35%Nb; 18,34%Fe–36,66%Cu–45%Nb. This study aims to evaluate the behavior of metal matrices to better choose the type of matrix to be used in the manufacture of diamond tools. The metal powders were blended according to the compositions of each metal matrix and then hot pressed at 800º /35MPa / 3min, thus occurring the sintering. The sintered samples of each metal matrix were conducted to the Abrasion Resistance test in order to verify the wear, for the accumulated times of 2, 6, 12 and 20 minutes. In these metal matrices, density, porosity and Vickers hardness (HV5) tests were performed to better understand the wear suffered by the samples. Thus, the metal matrix 25% Fe-50%Cu-25%Nb presented, in the general context of the properties and from the abrasive point of view, satisfactory results capable of replacing the NEXT 100 matrix.