Papers by Author: Fabio A. Deorsola

Abstract: Nanostructured Mg2Ni, Fe-doped and Ti-doped Mg2Ni alloys for hydrogen storage applications have been produced by means of Mechanically Activated Self-propagating High temperature Synthesis (MASHS). Different molar compositions of Fe and Ti (0.1; 0.3 and 0.5) have been studied in order to determine their influence in the hydrogen sorption properties. Different Mg-Ni based alloys have been tested in order to study their hydrogen sorption behavior. The hydrogenation was carried out in a Pressflow Gas Controller. Subsequently, the dehydrogenation process was conducted by means of a Differential Scanning Calorimetry (DSC) equipped with an H2 detector of the purged gas. The MASHS method has been demonstrated to be effective for the obtainment of nanostructured pure and doped Mg2Ni intermetallics. In addition, the materials produced showed hydrogen storage capacities superior to 4wt%, especially in the case of Fe-doped Mg2Ni and a slight reduction of desorption temperature was reached with Ti-doped Mg2Ni. Finally, the activation energy of the dehydrogenation process was evaluated and Ti-doped sample exhibited the lower activation energy value. Obtained results are promising for technological applications of Mg-based alloys.

Abstract: Nanostructured semiconductor metal oxides have played a central role in the gas sensing research field, because of their high sensitivity, selectivity and low response time. Among all the processes, developed for the synthesis of nanostructured metal oxides, gel combustion seems to be the most promising route due to low-cost precursors and simplicity of the process. It combines chemical gelation and combustion, involving the formation of a gel from an acqueous solution and an exothermic redox reaction, yielding to very porous and softly agglomerated nanopowders. In this work, nanostructured tin oxide, SnO2, and titanium oxide, TiO2, have been synthesized through gel combustion. Powders showed nanometric particle size and high specific surface area. The so-obtained TiO2 and SnO2 nanopowders have been used as sensitive element of resistive λ sensor and ethanol sensor respectively, realized depositing films of nanopowders dispersed in water onto alumina substrates provided with Pt contacts and heater. TiO2-based sensors showed at high temperature good response, fast response time, linearity in a wide range of O2 concentration and long-term stability. SnO2-based sensors have shown high sensitivity to low concentrations of ethanol at moderate temperature.

Abstract: The aim of this work is the preparation and study of the mechanisms of structure formation of dense ceramics based on the TiC–TiB2–MeO system obtained by pressure–assisted Self-propagating High-temperature Synthesis. SHS systems were selected on the basis of thermodynamic analysis as suitable to realise regimes of synthesis with formation of liquid phase allowing a full densification. It was observed that at the adiabatic temperature the liquid phase formed in the SHS products consists of either melted oxides or eutectic TiC–TiB2. The results of microstructural observations and mechanical characterization confirm that the metal oxides effectively promote the densification of the final products and the grain refinement of the SHSproduced ceramic materials.