Papers by Keyword: Reactive Milling

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Authors: Daniel Rodrigo Leiva, Elíria Maria Jesus Agnolon Pallone, Roberto Tomasi, Walter José Botta Filho
Authors: Elíria Maria Jesus Agnolon Pallone, V. Trombini, Walter José Botta Filho, Roberto Tomasi
Authors: Karolina Pereira dos Santos Tonello, Vânia Trombini, Ana Helena de Almeida Bressiani, José Carlos Bressiani
Abstract: Production of nanometric ceramic powders is one of the most recent advances in materials science. However the large scale production of some materials is still a challenge. There are two approaches to the fabrication of nanomaterials that results in powders with distinct characteristics. In high energy milling the particle size is reduced by mechanical forces to achieve nanosized particles. Another technique is reactive milling in which nanometric particles are synthesized by mechanically activated reactions. In this work NbC nanoparticles were produced by high energy milling of commercial NbC and by self-sustained high energy reactive milling of Nb2O5-Al-C powder mixture. The NbC particles were desagglomerated for 1h in a planetary mill. The obtained powders were characterized by X-ray diffraction, scanning electron microscopy and laser diffraction. The objective of this study was to compare the efficiency of two employed techniques to determine the most of producing nanoscale NbC.
Authors: Walter José Botta Filho, D.E. Hanai, B.N. Santana, N.R. de Oliveira Jr., Roberto Tomasi
Authors: Shi Xue Zhou, Qian Qian Zhang, Nai Fei Wang, Zong Ying Han, Wei Xian Ran, Chang Zhen Li, Chao Ding, Peng Bo Li
Abstract: Magnesium-based hydrogen storage materials were prepared by reactive milling of magnesium under hydrogen atmosphere with crystallitic carbon, prepared from anthracite coal, as milling aid. The XRD analysis shows that in the presence of 30 wt.% of crystallitic carbon, the Mg easily hydrided into β-MgH2 of crystal grain size 29.7 nm and a small amount of γ-MgH2 after 3 h of milling under 1 MPa H2. The enthalpy and entropy changes of the hydrogen desorption reaction are 42.7 kJ/mol and 80.7 J/mol K, respectively, calculated by the vant Hoff equation from the p-C-T data in 300-380°C.
Authors: V. Trombini, Elíria Maria Jesus Agnolon Pallone, F.C. Mello, Walter José Botta Filho, Roberto Tomasi
Authors: K. Tousimi, Walter José Botta Filho, Alain Reza Yavari
Authors: Daniel Rodrigo Leiva, André Castro De Souza Villela, Carlos de Oliveira Paiva-Santos, Daniel Fruchart, Salvatore Miraglia, Tomaz Toshimi Ishikawa, Walter José Botta Filho
Abstract: Magnesium complex hydrides as Mg2FeH6 are interesting phases for hydrogen storage in the solid state, mainly due to its high gravimetric and volumetric densities of H2. However, the synthesis of this hydride is not trivial because the intermetallic phase Mg2Fe does not exist and Mg and Fe are virtually immiscible under equilibrium conditions. In this study, we have systematically studied the influence of the most important processing parameters in reactive milling under hydrogen (RM) for Mg2FeH6 synthesis: milling time, ball-to-powder weight ratio (BPR), hydrogen pressure and type of mill. Low cost 2Mg-Fe mixtures were used as raw materials. An important control of the Mg2FeH6 direct synthesis by RM was attained. In optimized combinations of the processing parameters, very high proportions of the complex hydride could be obtained.
Authors: Oliver Gutfleisch, A. Bollero, M. Kubis, K.-H. Müller, Ludwig Schultz
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