CLAUDIO JOSE DA ROCHA
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Artigo IPEN-doc 25090 An alternative route to produce easily activated nanocrystalline TiFe powder2018 - FALCAO, R.B.; DAMMANN, EDGAR D.C.C.; ROCHA, C.J.; DURAZZO, M.; ICHIKAWA, R.U.; MARTINEZ, L.G.; BOTTA, W.J.; LEAL NETO, R.M.In this paper, an alternative process route to produce active nanocrystalline TiFe compound was investigated. First, TiH2 and Fe powders were dry co-milled in a planetary ball mill for 5e40 h. TiH2 was selected as precursor powder, instead of Ti powder, due its fragility, which has proved to be beneficial to decrease powders adherence on milling tools. In terms of loose powder mass, milling yields ranged from 90 to 95 wt.%. Next, milled powders were post-heated at 873 K under dynamic high-vacuum for TiFe synthesis reaction. First hydrogen absorption was verified in situ during the cooling process of samples (until the room temperature), being the amount of hydrogen absorbed and desorbed by this samples measured by automated Sievert's apparatus, under constant hydrogen flow rate of 9 cm3. min-1 (dynamic measurements). Besides to allowing the first absorption in situ, the investigated process route also allowed the production of the non-stoichiometric TiFe compound (rich in Ti) in samples milled for shorter times (5 and 10 h), both characteristics associated with maintaining the mechanical compound activity. Each sample absorbed hydrogen at 2 MPa during the cooling process, requiring no additional thermal activation cycles, since the samples milled for shorter times (mainly for 10 h) could absorb hydrogen for the first time more easily. However, the samples milled for longer times (25 and 40 h) shown better results in terms of reversible and storage capacities (0.73 and 0.94 wt.%, respectively).Resumo IPEN-doc 22476 Easily hydridable nanostructured TiFe from ball milled TiHsub(2) and Fe powders mixtures2015 - FALCAO, R.B.; DAMMANN, E.D.C.C.; ROCHA, C.J.; ICHIKAWA, R.U.; MARTINEZ, L.G.; DURAZZO, L.G.; LEAL NETO, R.M.Artigo IPEN-doc 22365 Fabrication of powder from ductile uranium alloys for use as nuclear dispersion2014 - DURAZZO, M.; LEAL NETO, R.M.; ROCHA, C.J.; CARVALHO, E.U. de; RIELLA, H.G.Resumo IPEN-doc 20465 Ball milling of TiHsub(2) and Fe powders mixture: An alternative route to synthesize hydridable TiFe2014 - FALCAO, R.B.; DAMMANN, E.D.C.C.; ROCHA, C.J.; ICHIKAWA, R.U.; MARTINEZ, L.G.; DURAZZO, M.; LEAL NETO, R.M.Artigo IPEN-doc 20547 Synthesis of TiFe compound from ball milled TiHsub(2) and Fe powders mixtures2014 - FALCAO, RAILSON B.; DAMMANN, EDGAR D.C.C.; ROCHA, CLAUDIO J. da; ICHIKAWA, RODRIGO U.; DURAZZO, MICHELANGELO; MARTINEZ, LUIS G.; LEAL NETO, RICARDO M.TiFe compound was produced by high-energy ball milling of TiH2 and Fe powders, followed by heating under vacuum. TiH2 was used instead of Ti in order to avoid the strong particles adhesion to grinding balls and vial walls. Mixtures of TiH2 and Fe powders were drymilled in a planetary mill for times ranging from 5 to 40 hours. The amount of sample, number and diameter of the balls were kept constant in all experiments. After milling, samples were heated under dynamic high-vacuum for the synthesis reaction. As-milled and heat-treated materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA). The mean crystallite sizes and microstrains were determined by XRD line profile analysis using the Warren-Averbach method. As-milled materials presented only Fe and TiH2 phases. Nanostructured TiFe compound was formed after heat treatment. TiH2 was effective for providing low adherence of the powders during milling.Resumo IPEN-doc 16657 An investigation on the mechanical alloying of TiF e compound by high-energy ball milling2009 - FALCÃO, R.B.; DAMMANN, E.D.C.C.; ROCHA, C.J.; LEAL NETO, R.M.Artigo IPEN-doc 12489 Mechanical activation of Nb75Al powder mixtures with different process control agents2007 - GONCALVES, V.S.; ROCHA, C.J.; LEAL NETO, R.M.Artigo IPEN-doc 15897 Obtencao do composto TiFe a partir da moagem de alta energia de misturas Ti+Fe e TiHsub(2)+Fe2010 - FALCAO, R.B.; DAMMANN, E.D.C.C.; ROCHA, C.J.; LEAL NETO, R.M.Artigo IPEN-doc 15677 An investigation on the high-energy ball milling of iron-titanium powder mixtures without process control agents2010 - LEAL NETO, RICARDO M.; FALCAO, RAILSON B.; DAMMANN, EDGAR D.C.C.; ROCHA, CLAUDIO J. daArtigo IPEN-doc 18397 Elaboração mecânica do composto TiFe a partir dos pós de TiHsub(2) e de Fe2012 - FALCÃO, R.B.; DAMMANN, E.D.C.C.; ROCHA, C.J.; LEAL NETO, R.M.