52 results on '"Luciano Pilloni"'
Search Results
2. Dense nanocrystalline W alloys: Enhancement of hardness and thermal stability by Al addition
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Francesco Torre, Teodor Huminiuc, Paolo Barra, Luciano Pilloni, Tomas Polcar, Antonio Rinaldi, Francesco Delogu, Roberto Orrù, Giacomo Cao, and Antonio Mario Locci
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General Medicine - Published
- 2023
3. 15/15 Ti Stainless Steel Welding Process Optimization for GEN IV Nuclear Application in the GEMMA Project Frame
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Luciano Pilloni, Claudio Testani, G. Barbieri, Daniele Mirabile Gattia, and F. Cognini
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Materials science ,Mechanics of Materials ,Mechanical Engineering ,Frame (networking) ,Metallurgy ,General Materials Science ,Process optimization ,Condensed Matter Physics ,Gemma ,Stainless steel welding - Abstract
This paper deals with activities carried out in the frame of GEMMA project on welded samples of 15/15 Ti stainless steel. The focus of GEMMA project has been on the investigation of material properties and associated welded joints for GEN IV nuclear plants. The RCC-MRx code uses the standard Base Metal Grade nomenclature (EN/ISO), but provides also additional specifications. Titanium stabilized “15-15Ti” stainless steel has been the primary choice for fuel cladding of current fast spectrum research reactor projects. The choice of cladding material is based on past experiences and the availability of material databases from similar steel grades proven in past sodium-cooled fast reactors programs [1-4]. On the basis of ENEA past experience, a strict specification has been written to realize a new heat treatment of this special stainless steel (SS). One of the main problems faced with this material is the high tendency to crack after the welding process. Several preliminary welding tests permitted to select TIG and laser welding processes for the 15/15 Ti SS. This fact because the main applications involve small thicknesses without filler material. The welding of the 15/15 Ti was performed using a fully automated TIG work station at ENEA CR-Casaccia. The base materials to evaluate the welding parameters were 15/15 Ti plates 100 X 170 X 3 mm welded under different shielding gas atmospheres and process parameters arrangements that permitted to obtain good quality joints avoiding catastrophic hot-cracking. The welded samples underwent a mechanical and metallographic characterization and the main results are here presented.
- Published
- 2021
4. Design of a fluorescent and clickable Ag38(SRN3)24 nanocluster platform: synthesis, modeling and self-assembling
- Author
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Martina De Angelis, Gaetano Campi, Luciano Pilloni, Mauro Satta, Lorenza Suber, Alessandro Fortunelli, Amedeo Palma, Luca Sementa, Giuliana Righi, Ludovica Primitivo, Alessandra Del Giudice, and Daniela Caschera
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Materials science ,XRD ,nanoclusters ,UV-vis ,Bioengineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Catalysis ,Nanoclusters ,silver ,General Materials Science ,Clickable ,Small-angle X-ray scattering ,theoretical modeling ,General Engineering ,SAXS ,General Chemistry ,fluorescence spectroscopy ,021001 nanoscience & nanotechnology ,Fluorescence ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Surface modification ,0210 nano-technology ,Biosensor ,Stoichiometry ,ATR-FTIR - Abstract
Fluorescent atomically precise Ag38(11-azido-2-ol-undecane-thiolate)24 nanoclusters are easily prepared using sodium ascorbate as a "green"reducer and are extensively characterized by way of elemental analyses, ATR-FTIR, XRD, SAXS, UV-vis, fluorescence spectroscopies, and theoretical modeling. The fluorescence and the atomically determined stoichiometry and structure, the facile and environmentally green synthesis, together with the novel presence of terminal azido groups in the ligands which opens the way to "click"-binding a wide set of molecular species, make Ag38(11-azido-2-ol-undecane-thiolate)24 nanoclusters uniquely appealing systems for biosensing, recognition and functionalization in biomedicine applications and in catalysis. This journal is
- Published
- 2021
5. Functionalized Magnetic Nanoparticles as Catalysts for Enantioselective Henry Reaction
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Ludovica Primitivo, Marzia Oneto Domenici, Lorenza Suber, Ilaria Ben Romdan, Martina De Angelis, Alessandra Ricelli, Giuliana Righi, Andrea Mastrodonato, Carla Sappino, Luciano Pilloni, Chiara Tatangelo, Sappino, C., Primitivo, L., De Angelis, M., Domenici, M. O., Mastrodonato, A., Romdan, I. B., Tatangelo, C., Suber, L., Pilloni, L., Ricelli, A., and Righi, G.
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Nitroaldol reaction ,General Chemical Engineering ,Enantioselective synthesis ,Nanoparticle ,Alcohol ,General Chemistry ,Diethylzinc ,Combinatorial chemistry ,Article ,Catalysis ,Chemistry ,chemistry.chemical_compound ,chemistry ,Magnetic nanoparticles ,asymmetric catalysis ,magnetic nanoparticles ,Henry reaction ,QD1-999 ,Superparamagnetism - Abstract
With the aim to easily recover and reuse the catalyst, an efficient amino alcohol catalyst previously tested in the asymmetric addition of diethylzinc to several aromatic aldehydes has been immobilized on proper functionalized superparamagnetic core-shell magnetite-silica nanoparticles and employed in the Henry reaction in the semi-homogeneous phase. The nanocatalyst exhibits a promising catalytic activity that remains unchanged in the three catalytic cycles performed. The results prove that highly efficient catalysts, by being immobilized on suitable magnetic nanosupports, can be easily recovered and reused, maintaining their catalytic behavior.
- Published
- 2019
6. Achievement of Ultrafine Grain structure by means of recrystallization treatments
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Carlo Cristalli, Oriana Tassa, Luciano Bozzetto, and Luciano Pilloni
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Nuclear and High Energy Physics ,Nuclear Energy and Engineering ,General Materials Science - Published
- 2022
7. Austenitization and Tempering Temperatures Effects on EUROFER 97 Steel
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Luciano Pilloni, Laura Alleva, Claudio Testani, and Andrea Di Schino
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Materials science ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,7. Clean energy ,010305 fluids & plasmas ,Mechanics of Materials ,0103 physical sciences ,General Materials Science ,Tempering ,0210 nano-technology - Abstract
EUROFER 97 is considered as standard steel for the nuclear applications in the case of high radiation density for first wall of a fast breeder reactors. Based on such consideration the microstructural behaviour of EUROFER 97 after thermo-mechanical processing is fundamental, since such materials properties are interesting also for innovative solar plants. In this paper the effect of thermo-mechanical behavior on the mechanical properties of EUROFER 97 has been analyzed by hot rolling followed by heat treatment on laboratory scale.A strong effect of reheating conditions before rolling on the material strength, due to an increase of hardenability following the austenite grain growth is found. A limited effect of the hot reduction and of the following tempering behavior is found in the considered deformation-range investigated. A loss of impact toughness is detected together with the hardness improvement.Mechanical properties are depending on the tempering temperature and an improvement of tensile yield stress (YS) and ultimate stress (UTS) was determined in tensile test carried on at T=550°C and T=650°C, e.g.: YS increase from about 400 MPa for standard EUROFER 97 [1] to about 550 MPa in samples treated by a tempering temperature of 720°C instead of the standard 760°C for EUROFER 97. Same trend has been found for UTS results.
- Published
- 2018
8. Design of a fluorescent and clickable Ag
- Author
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Gaetano, Campi, Lorenza, Suber, Giuliana, Righi, Ludovica, Primitivo, Martina, De Angelis, Daniela, Caschera, Luciano, Pilloni, Alessandra, Del Giudice, Amedeo, Palma, Mauro, Satta, Alessandro, Fortunelli, and Luca, Sementa
- Abstract
Fluorescent atomically precise Ag
- Published
- 2021
9. ZnS wurtzite ceramic fabrication by a simple and cost‐effective pressureless sintering method: A microstructure development overview
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Radenka Krsmanovic Whiffen, Elena Salernitano, Selene Grilli, Giuseppe Magnani, Francesca Mazzanti, Luciano Pilloni, and Amelia Montone
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grain size ,density ,ZnS ,SEM ,microstructure ,ceramics ,Two-step sintering - Abstract
The Two-Step Sintering (TSS) process is a useful method to obtain sintered materials of high density and to limit the grain growth associated with the final stage of the sintering process. One of the main advantages of this method is the lowering of the sintering temperature. The development of bulk, dense and small grain size in the wurtzite phase of the ZnS ceramic was investigated by using a micron-sized ZnS powder as a precursor material. The microstructure and morphology of the TSS-fabricated ZnS ceramic pellets were observed by Scanning Electron Microscopy (SEM) and compared to those produced by the conventional sintering process. The ZnS ceramic produced using the TSS method at 1100°C showed comparable density and a much finer microstructure (five times smaller grain size) than the ZnS ceramic produced using conventional sintering at 1250°C. It was demonstrated that the TSS process is a pressureless, simple and cost‐effective sintering method, able to deliver high density bulk, wurtzite phase ZnS ceramics with controlled grain size.  
- Published
- 2020
10. Electron Microscopy study of nanocrystalline wurtzite ZnS produced via a co-precipitation technique and its pyroelectric ceramics processed by 2-step- pressureless sintering
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Radenka Krsmanovic Whiffen, Loris Pietrelli, Luciano Pilloni, Giuseppe Magnani, Elena Salernitano, Selene Grilli, Francesca Mazzanti, and Amelia Montone
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zinc sulfide ,two-step sintering ,wurtzite ,electron microscopy ,pressure-less sintering ,ceramics ,7. Clean energy ,ZnS nanopowder - Abstract
The pyroelectric performances of non-ferroelectric pyroelectrics like wurtzite- based materials (e.g. AlN, GaN, CdS or ZnO) make them important, although not widely used, compared to the current state-of-the-art ferroelectrics. Their high chemical and thermal stability allows their use at high temperatures in air, whereas ferroelectrics become ineffective when heated beyond their Curie temperature (TC). Wurtzite based materials have a higher thermal conductivity allowing them to react faster to ambient temperature changes, their raw material costs are lower and many of them are eco-friendly. Current pyroelectrics applications are limited to portable systems or tasks needing only μW–mW power. To be commercially viable, we must improve the current low efficiency of pyroelectric systems and intrinsically enhance the pyroelectric properties of modern materials through suitable doping or material engineering. We chose to study hexagonal wurtzite phase of ZnS, among the structurally simplest of pyroelectrics, as a possible energy harvesting material. An easy synthesis method – a co-precipitation technique, was tailored for nanocrystalline wurtzite ZnS production. This method is easy to scale-up and our next step is to build an in-house pilot plant that will produce substantial amounts of wurtzite ZnS nano-powder in an environmentally friendly and cost-effective manner. We further investigated the development of bulk, dense pyroelectric ceramics by the Two-Step Sintering (TSS) fabrication process, using as the precursor material both a micron-sized commercial powder of the ZnS cubic and hexagonal phases mixture, and an in-house produced wurtzite ZnS nanopowder. The TSS was chosen as being a pressureless, simple and cost‐effective sintering method for obtaining high density materials with controlled grain growth operating at a lower temperature than the conventiona process. Electron Microscopy techniques helped us to study the microstructure and morphology of both the precursor nanopowders and the obtained ceramics. Acknowledgement: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 797951.
- Published
- 2020
- Full Text
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11. Irradiation hardening and ductility loss of Eurofer97 steel variants after neutron irradiation to ITER-TBM relevant conditions
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Xiang Chen, Tim Graening, Dmitry Terentyev, Michael Rieth, Luciano Pilloni, Thak Sang Byun, Athina Puype, Josina W. Geringer, Steven J. Zinkle, Arunodaya Bhattacharya, Jean Henry, Jordan D. Reed, Yutai Katoh, Bhattacharya, A., Chen, X., Graening, T., Geringer, J. W., Reed, J., Henry, J., Pilloni, L., Terentyev, D., Puype, A., Byun, T. S., Katoh, Y., Rieth, M., and Zinkle, S. J.
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Neutron irradiation ,Materials science ,Eurofer97 steel ,Tensile properties ,Mechanical Engineering ,Metallurgy ,Indentation hardness ,Nuclear Energy and Engineering ,fracture ,Hardening (metallurgy) ,General Materials Science ,Reduction in area ,Tempering ,Irradiation ,Irradiation-hardening ,Elongation ,Ductility ,High Flux Isotope Reactor ,Civil and Structural Engineering ,Tensile testing - Abstract
Ten Eurofer97 steel variants, produced by non-standard fabrication-processing routes and modified alloying chemistries, were studied by neutron irradiations in the high flux isotope reactor. The irradiations were performed to ITER-TBM relevant conditions of ∼255–350 °C, 2.94–3.24 dpa. We quantified the irradiation-induced degradation of the steels using mechanical property tests. All the steels suffered from irradiation hardening, where a significant increase in Vickers microhardness and yield stress (σYS) occurred, accompanied with severe loss of tensile elongation. The extent of hardening was material dependent. For Tirr = 300±30 °C, most steels showed σYS increase in the range of ∼30% to as high as ∼66%, except for a low temperature tempered steel with σYS increase below 15%. Despite large losses in elongation, most failures were ductile. Significant post-necking ductility was retained with reduction in area (RA) between 65–75%, but
- Published
- 2021
12. Technological aspects in blanket design: Effects of micro-alloying and thermo-mechanical treatments of EUROFER97 type steels after neutron irradiation
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Gerald Pintsuk, Pilar Fernández, A. Puype, Tim Gräning, D. Terentyev, G. Aiello, Arunodaya Bhattacharya, Xiang Chen, E. Simondon, Luciano Pilloni, Jordan D. Reed, Yutai Katoh, Jean Henry, Mikhail A. Sokolov, H.-C. Schneider, Lance Lewis Snead, C. Cristalli, Josina W. Geringer, Michael Klimenkov, O. Tassa, Michael Rieth, Rieth M., Simondon E., Pintsuk G., Aiello G., Henry J., Terentyev D., Puype A., Cristalli C., Pilloni L., Tassa O., Klimenkov M., Schneider H.-C., Fernandez P., Graning T., Chen X., Bhattacharya A., Reed J., Geringer J.W., Sokolov M., Katoh Y., and Snead L.
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Materials science ,Mechanical Engineering ,fracture toughne ,Metallurgy ,EUROFER97 ,Fracture mechanics ,Fractography ,Blanket ,Microstructure ,post irradiation examination ,embrittlement ,Nuclear Energy and Engineering ,Operating temperature ,Ultimate tensile strength ,General Materials Science ,Irradiation ,thermo-mechanical treatment ,ddc:620 ,neutron irradiation ,Engineering & allied operations ,High Flux Isotope Reactor ,Civil and Structural Engineering - Abstract
Presently available data on neutron irradiation damage raise doubts on the feasibility of using EUROFER97 steel for a water-cooled starter blanket in a DEMO reactor, since the ductile-to-brittle transition temperature (DBTT) increases significantly for irradiation temperatures below 350°C. The additional DBTT shift caused by H and He transmutation can only be estimated based on very few results with isotopically tailored EUROFER97 steel. Conservative calculations show that the DBTT of EUROFER97 steel could exceed the operating temperature in water-cooled starter blankets within a relatively short time period. This paper presents results from a EUROfusion funded irradiation campaign that was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. The paper compares ten newly developed reduced activation ferritic-martensitic (RAFM) steels irradiated to a nominal dose of 2.5 dpa at 300°C. The post-irradiation experiments using Small Specimen Test Technology included hardness, tensile, and fracture mechanics tests combined with fractography and microstructure analysis are presented. Results show that micro-alloying EUROFER97-type steels influenced the mechanical properties but a dominating impact on irradiation damage resistance could not be identified. In contrast, specific thermo-mechanical treatments lead to better DBTT behavior. Discussion about irradiation response to heat treatment conditions is also given. Despite requiring data also at high dpa values, the results indicate that with these modified materials an increased lifetime and potentially also an increased operating temperature window can be achieved compared to EUROFER97.
- Published
- 2021
13. Ultrathin and stable Nickel films as transparent conductive electrodes
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I. Di Sarcina, Maria Luisa Grilli, Antonio Rinaldi, Angela Piegari, Simone Bossi, Luciano Pilloni, Pilloni, L., Rinaldi, A., Bossi, S., Di Sarcina, I., Grilli, M. L., and Piegari, A.
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Fabrication ,Materials science ,Scanning electron microscope ,Transparent electrodes ,chemistry.chemical_element ,Nanotechnology ,Nickel ,Metal films ,Materials Chemistry ,Surface roughness ,Transmittance ,Transparent conducting film ,business.industry ,Metals and Alloys ,Indium-free electrode ,Ultra-thin films ,Surfaces and Interfaces ,Indium-free electrodes ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Indium tin oxide ,Metal film ,chemistry ,Electrode ,Ultra-thin film ,Optoelectronics ,business - Abstract
Ultrathin stable transparent conductive nickel films were deposited on quartz substrates by radio frequency sputtering at room temperature. Such films showed visible transmittance up to 80% and conductivity up to 1.8 × 104 S/cm, further increased to 2,3 × 105 S/cm by incorporation of a micrometric silver grid. Atomic force microscopy and scanning electron microscopy revealed quite compact, smooth and low surface roughness films. Excellent film stability, ease, fast and low cost process fabrication make these films highly competitive compared to indium tin oxide alternative transparent conductors. Films were characterized regarding their morphological, optical and electrical properties. © 2015 Elsevier B.V.
- Published
- 2015
14. Development of innovative steels and thermo-mechanical treatments for DEMO high operating temperature blanket options
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L. Bozzetto, O. Tassa, R. Sorci, Luciano Pilloni, L. Masotti, C. Cristalli, Masotti, L., Pilloni, L., and Cristalli, C.
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Nuclear and High Energy Physics ,Materials science ,Materials Science (miscellaneous) ,Alloy ,Ausforming ,engineering.material ,Blanket ,7. Clean energy ,01 natural sciences ,010305 fluids & plasmas ,Carbide ,Operating temperature ,0103 physical sciences ,Tensile ,Tempering ,Charpy ,010302 applied physics ,Metallurgy ,Creep ,EUROFER 97 ,Thermo-mechanical treatment ,RAFM steels ,lcsh:TK9001-9401 ,Nuclear Energy and Engineering ,engineering ,Hardening (metallurgy) ,lcsh:Nuclear engineering. Atomic power - Abstract
Among the options currently taken into account for the realization of the first DEMO reactor there are the “helium-cooled” and the “dual coolant” breeding blanket. Therefore the high temperature (650 °C) behavior of the proposed innovative martensitic alloys should be improved, namely the frame of the hereby reported activities is the development of martensitic alloys more resistant to creep, suitable to tolerate such a high operating temperature. In order to improve the high temperature mechanical properties, concerning the alloy design strategies, two alternative routes are proposed; the effect of Nitrogen and Tungsten increase are taken into account as well as the addition of carbo-nitride forming elements, like Vanadium, combined with the “ausforming” thermo-mechanical treatments. Two alloys have been designed and a special thermo-mechanical treatment on Eurofer 97-2 is proposed. The “ausforming” treatment, consisting in a sort of hot-working at a lower temperature with respect to the austenitization one after the austenitization stage, is aimed at the achievement of a beneficial dislocation “pinning” at high temperature due to carbide precipitation. Generally the improvement of tensile properties is associated to the hardening of the steel due to dislocation network and precipitation effects. This hardening is accompanied by a DBTT increase to markedly higher values with respect to Standard Eurofer. The proposed materials should be, in any case, at least room temperature ductile in order to undergo safe manufacturing and assembling processes. Therefore the issue of the DBTT increase has been taken into account by tuning the tempering temperature adequately. The two variations from chemical composition of Eurofer 97 have been casted and the thermo-mechanical treatments have been selected by means of SEM and hardness measurements to tune grain size and precipitation of carbides. The outcomes of the preliminary mechanical characterization (tensile, creep and impact tests) will be discussed in this paper. Keywords: EUROFER 97, RAFM steels, Thermo-mechanical treatment, Ausforming, Tensile, Creep, Charpy
- Published
- 2018
- Full Text
- View/download PDF
15. High-Temperature Oxidation and Oxide Scale Formation in Plasma-Sprayed CoNiCrAlYRe Coatings
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Emanuele Serra, Luciano Pilloni, A. Brentari, C. Blasi, G. Di Girolamo, Serra, E., Pilloni, L., Blasi, C., and Di Girolamo, G.
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Materials science ,Scanning electron microscope ,Metallurgy ,Metals and Alloys ,Oxide ,Energy-dispersive X-ray spectroscopy ,Atmospheric-pressure plasma ,Condensed Matter Physics ,Corrosion ,Superalloy ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Porosity ,Thermal spraying - Abstract
MCrAlY coatings are usually adopted to improve the environmental resistance of Ni-based superalloy components of turbine engines against high-temperature oxidation and hot corrosion. In this work, CoNiCrAlYRe coatings were produced by atmospheric plasma spraying. The coatings exhibited relatively low oxygen content and porosity. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that the high-temperature exposure at 1383ᅠK (1110ᅠᄚC) promoted the growth of an oxide scale on the top surface being composed of a continuous and dense Al2O3 inner layer followed by an outer mixed layer (Cr2O3 and spinels). The oxide scale was mainly composed of Al2O3, while the formation of mixed oxides occurred at lesser extent. After high-temperature exposure, the formation of internal oxides in some areas reduced the inter-lamellar cohesion, so that a decrease in microhardness was found.
- Published
- 2014
16. Pure magnetic hard fct FePt nanoparticles: Chemical synthesis, structural and magnetic properties correlations
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Gabriele Barrera, Luciano Pilloni, Lorenza Suber, Pierluigi Cossari, Federica Celegato, Marco Coïsson, Giada Marchegiani, Paolo Maria Eugenio Icilio Allia, F Padella, Paola Tiberto, Alessandro Chiolerio, E.S. Olivetti, and L Barba
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Nanostructure ,Materials science ,Nanoparticle ,Nanotechnology ,Thermal treatment ,Magnetic nanoparticles ,FePt nanoparticles ,Hard magnetic materials ,Condensed Matter Physics ,Magnetic materials ,Nanostructures ,Chemical synthesis ,Powder diffraction ,Magnetic properties ,Particle aggregation ,Tetragonal crystal system ,Chemical engineering ,Phase (matter) ,Particle ,General Materials Science - Abstract
FePt nanoparticles, containing a near-equal atomic percentage of Fe and Pt, with a face centered tetragonal structure ( fct ), are challenging for potential applications in high performance permanent magnets and high density data storage. In this study, we report on the chemical synthesis, carried out both solvothermally and hydrothermally in autoclave reacting iron (III) acetylacetonate and platinum (II) acetylacetonate with tri- or tetra-ethylene glycol, these employed as solvents, reducers and particle surface protecting agents as well. In both methods, a subsequent thermal treatment at high temperatures is necessary to transform the magnetic soft face centered cubic ( fcc ) phase to the hard fct one. Organic low-weight molecules, generally used to protect the nanoparticle surface and avoid particle aggregation, are decomposed by the thermal treatment resulting in particle aggregation and coalescence phenomena; on the contrary, in this case, a polymer matrix is formed as particle protecting agent and, by thermally treating the hydrothermally prepared nanoparticles up to 750 °C for 1 h, the pure magnetic hard fct phase is obtained while preserving the nanostructure. A detailed study is carried out on FePt nanoparticle structure ( fcc and fct phases) and correlated to the magnetic properties of the system.
- Published
- 2014
17. Microstructure and Wear Behavior of Plasma-Sprayed Nanostructured WC-Co Coatings
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Francesco Marra, Jacopo Tirillò, Luciano Pilloni, Giovanni Pulci, Giovanni Di Girolamo, Teodoro Valente, Pilloni, L., and Di Girolamo, G.
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Marketing ,Materials science ,Decarburization ,Scanning electron microscope ,Metallurgy ,Atmospheric-pressure plasma ,Cermet ,Tribology ,Condensed Matter Physics ,Microstructure ,Indentation hardness ,Plasma sprayed ,Materials Chemistry ,Ceramics and Composites - Abstract
Atmospheric plasma spraying of WC-Co particles with standard gas mixtures (Ar-H2) typically results in largely decarburized coatings with relatively low wear resistance. To fabricate cermet coatings with enhanced tribological properties, nanostructured WC-Co coatings were plasma sprayed using two different process gas mixtures. Phase composition and microstructure were investigated by X-ray diffraction and scanning electron microscopy, respectively. Microhardness increased by increasing the amount of retained WC grains in coating microstructure. Friction and wear properties, measured under dry sliding conditions, strongly depended on the degree of decarburization. They were comparable to those of conventional coatings produced using identical conditions. © 2012 The American Ceramic Society.
- Published
- 2012
18. Preparation and characterization of close-packed nanostructured sol–gel ceria thin films prepared using cerium-sec-butoxide as precursor
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Maria Cristina Ferrara, Luciano Pilloni, Saverio Mazzarelli, Anna Maria Laera, Leander Tapfer, and Emanuela Piscopiello
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Materials science ,Silicon ,Inorganic chemistry ,chemistry.chemical_element ,General Chemistry ,Substrate (electronics) ,Condensed Matter Physics ,Nanocrystalline material ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Cerium ,chemistry ,Chemical engineering ,Phase (matter) ,Materials Chemistry ,Ceramics and Composites ,Crystallite ,Thin film ,Sol-gel - Abstract
Polycrystalline, close-packed, homogeneous nanostructured ceria thin films were prepared by sol–gel process via dip-coating technique on soda-lime glass and (100)-oriented Si substrates. To produce the films, a sol was prepared using, as precursor, a home made cerium sec-butoxide dissolved in secondary butanol. The chemical composition, the microstructural/morphological characteristics and the optical properties of the coatings were investigated in detail. The experimental results clearly demonstrate that the ceria films are nanocrystalline (CeO2, cubic phase $$ {\text{Fm}}\bar{3}{\text{m}} $$ ) with an average grain size of about 2–3 nm for the samples grown on glass and of about 4–5 nm for the samples grown on silicon. The analyses of ceria layers grown on silicon show that the ceria coatings are free from organic residues and that a Si-oxide layer is formed at the film/substrate interface. The optical results evidence a red shift of the energy gap of about 0.5 eV that can be ascribed to conversion of relevant Ce4+ sites to Ce3+ sites and a consequent creation of oxygen vacancy at the surface of the ceria grains.
- Published
- 2011
19. Microstructural and thermal properties of plasma sprayed mullite coatings
- Author
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Luciano Pilloni, C. Blasi, Monica Schioppa, and Giovanni Di Girolamo
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Materials science ,Process Chemistry and Technology ,Metallurgy ,Recrystallization (metallurgy) ,Mullite ,Thermal treatment ,engineering.material ,Microstructure ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,law.invention ,Differential scanning calorimetry ,Coating ,law ,Materials Chemistry ,Ceramics and Composites ,engineering ,Crystallization ,Composite material - Abstract
Thick mullite (3Al 2 O 3 –2SiO 2 ) coatings were fabricated by atmospheric plasma spraying (APS) in a mixture of crystalline and amorphous phases, as confirmed by X-ray diffraction (XRD) analysis. The coatings were isothermally heat treated in order to study recrystallization mechanism of the glassy phase. The morphology and the microstructure of both mullite feedstock and coatings were investigated by using scansion electron microscopy (SEM). The porosity of as-sprayed coating was in the range between 2 and 3% and substantially remained unchanged after thermal treatment. The thermal expansion of as-sprayed and annealed coatings was measured during heating up to the temperature of crystallization and the corresponding high-temperature extent of shrinkage was calculated. The differential scanning calorimetry (DSC) curves at different heating rates showed a sharp exothermic peak between 1243 and 1253 K, suggesting a rapid recrystallization of the amorphous phase. Finally, the heat capacity of recrystallized mullite coating was measured by DSC experiments. It was approximately 1.02 × 10 3 J/kg K at 373 K and increased with increasing test temperature.
- Published
- 2010
20. A metal hydride–polymer composite for hydrogen storage applications
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Franco Padella, Aurelio La Barbera, Marzia Pentimalli, Luciano Pilloni, and Enrico Imperi
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chemistry.chemical_classification ,Materials science ,Renewable Energy, Sustainability and the Environment ,Hydride ,Composite number ,Alloy ,technology, industry, and agriculture ,Energy Engineering and Power Technology ,Polymer ,engineering.material ,Hot pressing ,Hydrogen storage ,Fuel Technology ,Nuclear Energy and Engineering ,chemistry ,Coating ,engineering ,Composite material ,Ball mill - Abstract
To address the issue of the breakdown into fine powders that occurs in the practical use of metal hydrides, the possibility of using a polymeric material as a matrix that contains the active metal particles was experimentally assessed. A ball milling approach in the tumbling mode was used to develop a metal hydride–polymer composite with a high metal to polymer weight ratio. The alloy powder was blended with the polymer and a coating of the metal particles was obtained. The composite was consolidated by hot pressing and the pellets were characterized in terms of their hydriding–dehydriding properties. The materials did not show significant losses in either loading capacity or kinetic properties. The polymeric matrix resulted as being stable under hydrogen cycling. Further, from SEM observation it was confirmed that the metal powders remained embedded in the polymeric matrix even after a number of cycles and that the overall dimensional integrity was retained.
- Published
- 2009
21. Microstructural and Kinetic Investigation of Hydrogen Sorption Reaction of MgH2/Nb2O5Nanopowders
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D. Mirabile Gattia, Annalisa Aurora, Amelia Montone, Luciano Pilloni, M. Vittori Antisari, E. Todini, and M. R. Mancini
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Thermogravimetric analysis ,Materials science ,Hydrogen ,Scanning electron microscope ,Mechanical Engineering ,Magnesium hydride ,Composite number ,Analytical chemistry ,chemistry.chemical_element ,Sorption ,Industrial and Manufacturing Engineering ,Catalysis ,chemistry.chemical_compound ,Hydrogen storage ,chemistry ,Chemical engineering ,Mechanics of Materials ,General Materials Science - Abstract
MgH2/Nb2O5 composite is one of the most promising candidates for the hydrogen delivery. The performances of these materials are usually improved by mechanical milling because a finer distribution of the catalyst and the induction of defects on the particles accelerate the hydrogen sorption kinetic of the powders. Aiming at elucidating the factors responsible for this improvement, the effect on the reaction kinetics induced by nanometric and micrometric Nb2O5 powders has been investigated by a Sievert type apparatus. Nanometric additive imparts excellent performances in comparison to the micrometric one. The activation of the sample by sorption cycling has been investigated. In order to elucidate the role of the catalyst, a metallographic study of partially desorbed MgH2/Nb2O5 composite has been applied for the first time. The powders have been also characterized by X-ray diffraction and thermal gravimetric analysis.
- Published
- 2009
22. Scanning electron microscopy of partially de-hydrogenated MgH2 powders
- Author
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Marco Vittori Antisari, M. Rita Mancini, Daniele Mirabile Gattia, Luciano Pilloni, Annalisa Aurora, and Amelia Montone
- Subjects
Phase transition ,Materials science ,Microscope ,Scanning electron microscope ,Mechanical Engineering ,Metals and Alloys ,Analytical chemistry ,Nucleation ,General Chemistry ,Microstructure ,law.invention ,Hydrogen storage ,Mechanics of Materials ,law ,Desorption ,Materials Chemistry ,Sample preparation - Abstract
The sorption behavior of MgH2 is the subject of numerous investigations concerning the safe hydrogen storage in metallic hydrides. With the purpose of integrating kinetic studies on the MgH2–Mg phase transformation with the analysis of the local microstructure, we have developed an experimental method for the metallographic examination by Scanning Electron Microscopy of partially desorbed MgH2 powders. The setting of the microscope and the sample preparation procedure have been optimized for highest contrast between Mg and MgH2, based on different electron emissions. In these experimental conditions the two phases can be clearly detected even in critical condition when strongly scattering catalyst particles are present. The method has been tested on a set of ball milled MgH2 samples either pure or containing Fe as catalyzing agent. A complete information on the spatial distribution of all the phases constituting the sample can be obtained by integrating observations carried out at different primary beam energies with different signals. As far as the desorption behavior is concerned, SEM analysis shows that the MgH2–Mg phase transition is strongly affected by catalyst particles which, in the present case, appear to support the nucleation step in the phase transformation sequence.
- Published
- 2009
23. Tribological Characterization of WC-Co Plasma Sprayed Coatings
- Author
-
Luciano Pilloni, Giovanni Pulci, Francesco Marra, and Giovanni Di Girolamo
- Subjects
Toughness ,Materials science ,Decarburization ,Metallurgy ,atmospheric plasma spraying ,cermet coatings ,high velocity oxygen fuel ,Atmospheric-pressure plasma ,Cermet ,Tribology ,engineering.material ,Microstructure ,Amorphous solid ,Coating ,Materials Chemistry ,Ceramics and Composites ,engineering - Abstract
Atmospheric plasma spraying of WC coatings is typically characterized by increased decarburization, with a consequent reduction of their wear resistance. Indeed, high temperature and oxidizing atmosphere promote the appearance of brittle crystalline and amorphous phases. However, by using a high helium flow rate in a process gas mixture, plasma spraying may easily be optimized by increasing the velocity of sprayed particles and by reducing the degree of WC dissolution. To this purpose, a comparative study was performed at different spray conditions. Both WC-Co powder and coating phases were characterized by X-ray difraction. Their microstructure was investigated by scanning electron microscopy. Mechanical, dry sliding friction, and wear tests were also performed. The wear resistance was highly related to both microstructural and mechanical properties. The experimental data confirmed that high-quality cermet coatings could be manufactured by using optimized Ar-He mixtures. Their enhanced hardness, toughness, and wear resistance resulted in coatings comparable to those sprayed by high velocity oxygen-fuel.
- Published
- 2009
24. Electro-deposition on carbon black and carbon nanotubes of Pt nanostructured catalysts for methanol oxidation
- Author
-
Luciano Pilloni, L. Giorgi, Alessia Cemmi, Mauro Pasquali, Rossella Giorgi, Emanuele Serra, and C. Paoletti
- Subjects
Hydrogen ,Renewable Energy, Sustainability and the Environment ,electro-catalytic activity ,electro-deposition techniques ,pefcs ,pt electro-catalysts ,Analytical chemistry ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Carbon black ,Carbon nanotube ,Electrochemistry ,Catalysis ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Methanol ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Cyclic voltammetry ,Carbon - Abstract
An electrochemical method for the Pt nanoparticles deposition on porous and high surface carbon substrates (carbon black and carbon nanotubes), as an alternative way to prepare gas diffusion electrodes for polymer electrolyte fuel cells (PEFCs), is herein described. Pt nanoparticles well distributed and localized on the electrode surface were obtained by using an electric field. The electro-catalysts were prepared by single and multiple pulse galvanostatic polarizations in 1 M sulphuric acid + 5 mM exachloroplatinic acid solution. Chemical analysis, cyclic voltammetry and field emission gun scanning electron microscopy were used to determine the electrochemical features of Pt deposits and the influence of electro-deposition method on their nano-morphology. Electro-catalytic performances were studied by investigating the methanol oxidation reaction and the results are presented in form of surface specific activity and mass specific activity to take into account the electrochemical real surface and Pt loading. A comparison with commercial E-TEK Pt/C catalysts, prepared by traditional chemical reduction and heat treatment in hydrogen, shows that the electrodeposited catalyst presents higher activity at lower Pt loading.
- Published
- 2008
25. The influence of hydrogen on the fatigue behaviour of base and gas tungsten arc welded Eurofer
- Author
-
Marie-Françoise Maday and Luciano Pilloni
- Subjects
Nuclear and High Energy Physics ,Materials science ,Hydrogen ,Metallurgy ,chemistry.chemical_element ,Welding ,Microstructure ,Fatigue limit ,law.invention ,Cracking ,Nuclear Energy and Engineering ,chemistry ,law ,General Materials Science ,Grain boundary ,Embrittlement ,Hydrogen embrittlement - Abstract
Room temperature hydrogen embrittlement susceptibility of Eurofer base-metal and gas-tungsten-arc-welded joint has been investigated by fully-reversed load-control low cycle fatigue. The tests were run on specimens subjected to electrochemical charging before and during cyclic stressing. Compared to the uncharged condition, increasing amounts of hydrogen in base-steel caused fatigue life reduction by promoting premature cracking of either grain boundaries or cleavage planes. Examination of fracture morphologies indicated that the underlying embrittlement mechanisms likely correlated with plastic flow alteration and interatomic bond decohesion, both induced by hydrogen. Specimen-to-specimen response variability by test replication was accounted for in terms of Eurofer material heterogeneity, based on relevant experimental indexes. This interpretation was consistent with the well known sensitivity to microstructure of hydrogen embrittlement processes, and explained the large scatter of fatigue lives and failure modes subsequently observed in equivalently charged Eurofer weld samples.
- Published
- 2007
26. Arc-Discharge Synthesis of Carbon Nanohorns and Multiwalled Carbon Nanotubes
- Author
-
Daniele Mirabile Gattia, Luciano Pilloni, V. Contini, Marco Vittori Antisari, Renzo Marazzi, and Amelia Montone
- Subjects
Materials science ,Carbon nanofiber ,Mechanical Engineering ,chemistry.chemical_element ,Condensed Matter Physics ,Cathode ,Amorphous solid ,law.invention ,Electric arc ,Amorphous carbon ,chemistry ,Chemical engineering ,Mechanics of Materials ,law ,Carbide-derived carbon ,General Materials Science ,Carbon nanotube supported catalyst ,Composite material ,Carbon - Abstract
Carbon nanohorns and multiwalled carbon nanotubes have been synthesized by DC arcdischarge carried out at room pressure in air and Ar-enriched environment, by a specially designed experimental device. The resulting nanostructured material, characterized by electron microscopy and X-ray diffraction, shows different structures according to the condensation channels through which the sublimated carbon atoms are re-condensed in the solid state. Multi-Walled Carbon Nano- Tubes are mainly found in the hard crust formed at the cathode, while nano-horned particles can be recovered from a cylindrical collector surrounding the discharge. Further material, rag-like shaped and with an amorphous structure, can be collected in the reaction area. When the discharge occurs under Ar atmosphere, a larger quantity of this latter phase is synthesized. This suggests that the atmospheric oxygen could play an active role by burning the most reactive among the synthesized phases, like amorphous carbon contributing so to an “in situ” purification of the raw material.
- Published
- 2006
27. Hydrogen effects on the tensile and fatigue properties of Eurofer’97
- Author
-
Luciano Pilloni and Marie-Françoise Maday
- Subjects
Materials science ,Yield (engineering) ,Mechanical Engineering ,Fatigue limit ,Brittleness ,Nuclear Energy and Engineering ,Ultimate tensile strength ,General Materials Science ,Deformation (engineering) ,Composite material ,Ductility ,Embrittlement ,Civil and Structural Engineering ,Hydrogen embrittlement - Abstract
Hydrogen embrittlement (HE) of Eurofer’97 was investigated by means of constant extension rate tensile (CERT) and fully reversed load-control low cycle fatigue (LCF) tests, run at room temperature and under electrochemical charging before and during specimen deformation. Increasing H content from 1.6 to 5.6 wppm caused increasing ductility loss compared to air behaviour and increasing data scatter from replicated CERT tests in terms of embrittlement indexes and fracture modes. The same trend manifested itself on Eurofer fatigue lifetimes after cyclic loading below the monotonic yield, but to a major degree as frequency was lowered. Fractographic analysis under scanning electron microscope indicated that brittle cracking, which macroscopically involved intergranular (IG) or transgranular (TG) separation, included morphologies closely related to HE phenomena through plastic flow modification and/ or interface decohesion. Correlation of these results with H desorption spectra and microstructural assessments suggested that the origin of mechanical response variability from specimen-to-specimen with similar H levels could arise from material heterogeneity in terms of trap characteristics.
- Published
- 2005
28. Carbon Nanotube Growth on PAN‐ and Pitch‐Based Carbon Fibres by HFCVD
- Author
-
M.F. De Riccardis, Rossella Giorgi, D. Carbone, Nicola Lisi, E. Salernitano, Th. Dikonimos Makris, and Luciano Pilloni
- Subjects
Materials science ,Organic Chemistry ,chemistry.chemical_element ,Carbon nanotube ,Chemical vapor deposition ,Atomic and Molecular Physics, and Optics ,law.invention ,Nickel ,chemistry ,Impurity ,law ,Cluster (physics) ,General Materials Science ,Carbon nanotube supported catalyst ,Physical and Theoretical Chemistry ,Composite material ,Carbon ,Deposition (law) - Abstract
Carbon nanotubes (CNT) were grown on carbon fibres, both PAN‐ and pitch‐based, by hot filament chemical vapour deposition (HFCVD) using H2 and CH4 as precursors. Nickel clusters were electrodeposited on the fibre surfaces to catalyse the growth, and uniform CNT coatings were obtained on both PAN‐ and pitch‐based carbon fibres. Ni cluster features varied, depending on the deposition parameters, showing on average larger dimensions and denser distribution on pitch fibres. Multi‐walled CNTs with smooth walls and low impurity content were grown. The morphological features, both before and after the growth process, were characterised by SEM. This novel material based on carbon fibres coated with CNT, shows a potential for applications in polymeric matrix composites.
- Published
- 2005
29. Bias enhanced nucleation of diamond on Si(100) in a vertical straight hot filament CVD
- Author
-
Rossella Giorgi, E. Salernitano, Th. Dikonimos Makris, Luciano Pilloni, and Nicola Lisi
- Subjects
Silicon ,Chemistry ,Mechanical Engineering ,Nucleation ,Diamond ,chemistry.chemical_element ,General Chemistry ,Substrate (electronics) ,Chemical vapor deposition ,engineering.material ,Nanocrystalline material ,Electronic, Optical and Magnetic Materials ,Crystallography ,Chemical engineering ,X-ray photoelectron spectroscopy ,Materials Chemistry ,engineering ,Gas composition ,Electrical and Electronic Engineering - Abstract
The aim of the Bias Enhanced Nucleation (BEN) step is to increase the nucleation density during the CVD diamond growth process with respect to more traditional methods like scratching. Diamond seeds were grown in a HFCVD reactor with several vertical straight filaments and a double bias geometry allowing BEN over large area silicon substrates. The effect of the substrate temperature and the gas composition was studied. Spectroscopic and morphological characterisation has been performed on the substrates, both after the BEN and the subsequent growth process. The substrate temperature was found to be an important parameter controlling the nucleation. When the substrate temperature is above 1100 °C, both the nucleation and the growth resulted in nanocrystalline SiC while at lower temperature optimal diamond nucleation and growth were found. Simultaneously, intermediate phases between elemental and non-stoichiometric SiC were observed by XPS. Nucleation densities of 10 11 cm −2 and higher were obtained over a surface of several squared centimeters.
- Published
- 2005
30. Hydrogen Permeation Measurements on Alumina
- Author
-
E. Serra, G. Cosoli, Luciano Pilloni, and A. Calza Bini
- Subjects
Arrhenius equation ,Hydrogen ,Analytical chemistry ,chemistry.chemical_element ,Atmospheric temperature range ,Permeation ,Thermal diffusivity ,Hildebrand solubility parameter ,symbols.namesake ,chemistry ,Permeability (electromagnetism) ,Materials Chemistry ,Ceramics and Composites ,symbols ,Solubility ,Nuclear chemistry - Abstract
The aim of this work is to measure the hydrogen transport and solubility parameters in the commercial alumina. Measurements are conducted using a time-dependent permeation method over the temperature range 1273–1673 K with hydrogen driving pressures in the range 104–105 Pa (100–1000 mbar). A half-power pressure dependence (diffusion-limited permeation) of the permeation flux for alumina is observed. The Arrhenius expressions for the hydrogen permeability, diffusivity, and Sieverts' constant values obtained from a fitting to the whole temperature range are as follows: P=3.3·10−10 exp(−97420/RT) mol·m−1·s−1·Pa−1/2 D=9.7·10−8 exp(−79990/RT) m2·s−1 Ks=5.5·10−3 exp(−22540/RT) mol·m−3·Pa−1/2
- Published
- 2004
31. Issues of low activation brazing of SiCf/SiC composites by using alloys without free silicon
- Author
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B. Riccardi, S Libera, Jörg Woltersdorf, Traian Petrisor, Luciano Pilloni, Eckhard Pippel, and C.A. Nannetti
- Subjects
Nuclear and High Energy Physics ,Materials science ,Silicon ,Metallurgy ,Alloy ,Intermetallic ,chemistry.chemical_element ,engineering.material ,Microstructure ,Carbide ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,Silicon carbide ,engineering ,Brazing ,General Materials Science ,Composite material ,Eutectic system - Abstract
The paper presents a novel low activation brazing technique for SiCf/SiC composites. The brazing alloy does not contain free silicon and is based on the use of a Si–44Cr at.% eutectic and the intermetallic CrSi2 (melting temperatures 1390 and 1490 °C, respectively). These are advantageous because the melting point is low enough to avoid degradation of the advanced fibres and of the interphases in the composite, and the Si–Cr intermetallics are chemically compatible with silicon carbide. Both the eutectic and the intermetallic were prepared before brazing operations by melting a Si–Cr mixture. The joining was performed under vacuum (about 10−4 Pa). Systematic investigations of the microstructure and of the nanochemistry (TEM, EELS, ELNES) of the Si–Cr joints reveal that direct chemical Si–Si, Cr–C and Si–Cr bonds across the interface are responsible for the adhesion: the interfaces were proved to be nearly atomically sharp and adhesive. Altogether, this brazing procedure enables joints with sufficient strength and with a microstructure comparable with that of the starting powders to be obtained.
- Published
- 2004
32. Carbon nanotubes growth by HFCVD: effect of the process parameters and catalyst preparation
- Author
-
Nicola Lisi, Francesca Sarto, Th. Dikonimos Makris, E. Salernitano, Luciano Pilloni, Marco Alvisi, and Rossella Giorgi
- Subjects
inorganic chemicals ,Materials science ,Silicon ,Mechanical Engineering ,Oxide ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Substrate (electronics) ,Chemical vapor deposition ,Electronic, Optical and Magnetic Materials ,Catalysis ,law.invention ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Sputtering ,law ,Materials Chemistry ,Electrical and Electronic Engineering ,Thin film - Abstract
Carbon nanotubes (CNTs) were grown on nickel catalysts by hot filament chemical vapour deposition (HFCVD) using H 2 and CH 4 as gas precursors. CNTs with different characteristics were observed varying some growth parameters, such as the substrate temperature, the total pressure and the methane concentration. These parameters were optimised in order to obtain untangled CNTs with high density and smooth walls. Catalyst nanoparticles were obtained through the clustering of Ni thin films deposited by sputtering techniques. CNTs grown on samples with the silicon native oxide or with a SiO 2 coating between Si substrate and Ni film were compared. Catalytic layers and CNTs were characterised by SEM and XPS.
- Published
- 2004
33. High yield synthesis of pure alkanethiolate-capped silver nanoparticles
- Author
-
Luciano Pilloni, Alessio Mezzi, Lorenza Suber, Settimio Mobilio, Carla Cannas, Saulius Kaciulis, Carlo Meneghini, Giada Marchegiani, Alessandra Mari, Patrizia Imperatori, Alessandra, Mari, Patrizia, Imperatori, Giada, Marchegiani, Luciano, Pilloni, Alessio, Mezzi, Saulius, Kaciuli, Carla, Canna, Meneghini, Carlo, Mobilio, Settimio, and AND LORENZA, Suber
- Subjects
Dodecane ,Precipitation (chemistry) ,Analytical chemistry ,Nanoparticle ,Surfaces and Interfaces ,Condensed Matter Physics ,Silver nanoparticle ,chemistry.chemical_compound ,chemistry ,Transition metal ,Chemical engineering ,Reagent ,Yield (chemistry) ,Electrochemistry ,Molecule ,General Materials Science ,Spectroscopy - Abstract
One-phase, one-pot synthesis of Ag(0) nanoparticles capped with alkanethiolate molecules has been optimized to easily achieve a pure product in quantitative yield. We report the synthesis of dodecanethiolate-capped silver particles and the chemophysical, structural, and morphologic characterization performed by way of UV-vis, (1)H NMR, and X-ray photoelectron (XPS) spectroscopies, X-ray powder diffraction (XRD) and X-ray absorption fine structure analysis (XFAS), electron diffraction and high-resolution transmission electron microscopy (HR-TEM), and scanning and transmission electron microscopy (SEM and TEM). Depending on the molar ratio of the reagents (dodecylthiosulphate/Ag(+)), the mean Ag(0) particle size D(XRD) is tuned from 4 to 3 nm with a narrow size distribution. The particles are highly soluble, very stable in organic solvents (hexane, toluene, dichloromethane, etc.), and resistant to oxidation; the hexane solution after one year at room temperature does not show any precipitation or formation of oxidation byproducts.
- Published
- 2010
34. Performance of nanocomposites for preservation of artistic stones
- Author
-
Rosaria D'Amato, Cristina Giancristofaro, Luisa Caneve, Luciano Pilloni, Antonio Rinaldi, Franca Persia, Persia, F., Rinaldi, A., Pilloni, L., Caneve, L., and D'Amato, R.
- Subjects
Materials science ,Absorption of water ,Silicon ,Scanning electron microscope ,Nanoparticle ,chemistry.chemical_element ,Mineralogy ,titania nanoparticle ,silica nanoparticles ,engineering.material ,Contact angle ,stone conservation ,Coating ,Microscopy ,Composite material ,tone conservation ,Nanocomposite ,marble ,hydrophobic coatings. siloxanes polymers ,nanoeomposites ,titania nanoparticles ,chemistry ,engineering ,ilica nanoparticle ,nanoeomposite - Abstract
In this work, the effectiveness of nanocomposite surface treatments as protective systems for artistic stones was evaluated. Pyrolitic silica and titania nanoparticles were dispersed in a commercial silicon-based polymer and applied on marble and travertine samples. Artificial aging processes, both in climatic chamber and in solar box, were carried out to simulate real degradation processes in terms of photo-thermal effects and physical-chemical damage. The performances of the nanocomposites used as consolidant were evaluated comparatively by means of diverse diagnostic techniques, namely: scanning electron microscopy (SEM), laser induced fluorescence (LIF), ultrasonic technique, colorimetry, total immersion water absorption and contact angle. The results show that some properties of conservation materials can be improved by the presences of nanoparticles because they induce substantial changes of surface morphology of the coating layer and counter the physical damage observed during artificial weathering. © 2014 AIP Publishing LLC.
- Published
- 2014
35. Physical metallurgy of BATMAN II Ti-bearing martensitic steels
- Author
-
Luciano Pilloni, S Amato, F Attura, G. De Santis, A Carosi, A Calza-Bini, and G. Filacchioni
- Subjects
Austenite ,Nuclear and High Energy Physics ,Materials science ,Metallurgy ,Charpy impact test ,chemistry.chemical_element ,Microstructure ,Grain size ,Nuclear Energy and Engineering ,chemistry ,Martensite ,Particle-size distribution ,General Materials Science ,Chemical composition ,Titanium - Abstract
Seven laboratory experimental casts of 7–9% Cr Ti-bearing martensitic steels were obtained via VIM process. Plates of 25 mm thickness were produced by hot rolling. On each cast CCT diagrams and critical temperatures were determined. Several austenitizing treatments were performed to study the grain size evolution. The effect of microstructure on impact properties were finally investigated. This paper discusses the role of chemical composition on microstructural and physical properties and shows the beneficial effect either of low-temperature austenitizing or double-austenitizing steps on impact properties.
- Published
- 1998
36. Gamma-Ray-Induced Multi-Effect on Properties of Chalcogenide Glasses
- Author
-
Luciano Pilloni, Mauro Falconieri, Stefania Baccaro, Chen Guorong, Angelica Cecilia, Wang Hua, and Zhao Donghui
- Subjects
Scanning electron microscope ,business.industry ,Chemistry ,Band gap ,Chalcogenide ,Gamma ray ,Analytical chemistry ,Condensed Matter::Disordered Systems and Neural Networks ,Thermal expansion ,symbols.namesake ,chemistry.chemical_compound ,Optics ,Absorbed dose ,Materials Chemistry ,Ceramics and Composites ,symbols ,Astrophysics::Earth and Planetary Astrophysics ,Irradiation ,Raman spectroscopy ,business - Abstract
Gamma-ray irradiations induced various alterations in sulfur- and selenium-based chalcogenide glasses. The absorbed dose was in the range of 0.01–3.6 MGy. The glasses exhibit prominent sensitivity to γ-ray irradiation, characterized by changes in some of the physical properties of the glasses, e.g., optical transmission, optical band gap, density, and thermal expansion coefficient. The effects on glass structure and microscopic morphology were also studied by Raman spectra and scanning electron microscopic observations.
- Published
- 2006
37. Optimization of a Pyrolysis Procedure for Obtaining SiC-SiCf CMC by PIP for Thermostructural Applications
- Author
-
Luciano Pilloni, Emiliano Burresi, Daniele Nanni, F. Burgio, Daniele Caretti, Alida Brentari, Matteo Scafè, and Claudio Mingazzini
- Subjects
Austenite ,chemistry.chemical_classification ,chemistry.chemical_compound ,Materials science ,chemistry ,Xylene ,Nanoparticle ,Chemical vapor deposition ,Pyrolytic carbon ,Polymer ,Composite material ,Ceramic matrix composite ,Pyrolysis - Abstract
Polymer Impregnation Pyrolysis (PIP) is a cost effective technique for obtaining Ceramic Matrix Composites (CMC) modified with nanoparticles. Commercial UBE polymeric precursor (Tyranno polymer VL-100, diluted in xylene) of a SiC ceramic matrix (with 11 wt% O and 2 wt% Ti) was used to infiltrate 100x85x3 mmSuperscript text3 SiC felts (Tyranno ZM fibers, diameter 14 microns, 800 filament/yarn, 270 g/mSuperscript text2, with 9 wt% O and 1 wt% Zr), applying different pyrolysis procedures. In particular, pyrolysis was performed in two conditions: 1) at 1000 °C for 60 min; 2) at 900 °C for 120 min. A pyrolysis at 900 °C could be more convenient since it can be easily performed in a steel furnace, without a refractory lining. The SiC felts were pretreated by CVD (Chemical Vapour Deposition) in order to deposit a pyrolytic carbon interphase (about 0.1 microns). Impregnation was performed under vacuum, and drying was carried out in an explosion-proof heating oven. Pyrolysis at 900°C was performed in a AISI 310S austenitic steel furnace, under nitrogen flow. Geometric density was monitored during densification. Mechanical characterisation (bending tests at room temperature, following UNI EN 658-3:2002) was performed after 11 PIP cycles. The results were used to compare the influence of pyrolysis temperature on densification.
- Published
- 2012
38. Synthesis of Graphene Films on Copper Substrates by CVD of Different Precursors
- Author
-
Th. Dikonimos, Nicola Lisi, S. Gagliardi, Luciano Pilloni, E. Salernitano, Piero Morales, Mauro Falconieri, and Rossella Giorgi
- Subjects
Argon ,Materials science ,Hydrogen ,Graphene ,Analytical chemistry ,Order (ring theory) ,chemistry.chemical_element ,Copper ,Methane ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,X-ray photoelectron spectroscopy ,law ,symbols ,Raman spectroscopy - Abstract
In the present work, graphene films of the order of \(1\,\hbox{cm}^{2}\) were grown on copper foil substrates by CVD using hydrogen/methane or hydrogen/argon/ethanol mixtures as gas precursors. The growth processes were performed near \(1\hbox{,}000^{\circ}\hbox{C}\) both at atmospheric and low pressures. A system for the fast cooling of the sample, based on the fast extraction from the hot zone of the furnace, was implemented allowing for rapid decrease of the temperature below \(600^{\circ}\hbox{C}\) in few seconds. Samples grown under different conditions were analyzed by SEM, Raman spectroscopy and XPS with the aim to assess their characteristics and to refine the growth process.
- Published
- 2012
39. Sonochemical synthesis of versatile hydrophilic magnetite nanoparticles
- Author
-
Paola Tiberto, Paolo Maria Eugenio Icilio Allia, Giada Marchegiani, Luciano Pilloni, Lorenza Suber, Alessandro Chiolerio, Patrizia Imperatori, and Alessandra Mari
- Subjects
Materials science ,Acoustics and Ultrasonics ,Surface Properties ,Sonochemical synthesis ,Magnetite nanoparticles ,Magnetic properties ,XRD powder diffraction ,Inorganic Chemistry ,chemistry.chemical_compound ,Chemical Engineering (miscellaneous) ,Environmental Chemistry ,Organic chemistry ,Molecule ,Radiology, Nuclear Medicine and imaging ,Ultrasonics ,Particle Size ,Triethylene glycol ,Range (particle radiation) ,Ligand ,Organic Chemistry ,Magnetic hysteresis ,Ferrosoferric Oxide ,Surface-area-to-volume ratio ,Chemical engineering ,chemistry ,Covalent bond ,Nanoparticles ,Hydrophobic and Hydrophilic Interactions ,Superparamagnetism - Abstract
Hydrophilic magnetite nanoparticles in the size range 30–10 nm are easily and rapidly prepared under ultrasonic irradiation of Fe(OH) 2 in di- and tri-ethylene glycol/water solution with volume ratio varying between 7:3 and 3:7. Structural (XRD) and morphological (SEM) characterization reveal good crystalline and homogeneous particles whereas, when solvothermally prepared, the particles are inhomogeneous and aggregated. The sonochemically prepared particles are versatile, i.e. well suited to covalently bind molecules because of the free glycol hydroxylic groups on their surface or exchange the diethylene or triethylene glycol ligand. They can be easily transferred in hydrophobic solvents too. Room-temperature magnetic hysteresis properties measured by means of Vibrating Sample Magnetometer (VSM) display a nearly superparamagnetic character. The sonochemical preparation is easily scalable to meet industrial demand.
- Published
- 2011
40. Photocatalytic activity, hydrophilic and optical properties of nanocrystalline titania thin films prepared by sol-gel dip coating
- Author
-
Luciano Pilloni, A. Mevoli, Saverio Mazzarelli, Maria Cristina Ferrara, and Leander Tapfer
- Subjects
Anatase ,Materials science ,engineering.material ,Dip-coating ,Nanocrystalline material ,chemistry.chemical_compound ,chemistry ,Coating ,Chemical engineering ,Titanium dioxide ,Photocatalysis ,engineering ,Thin film ,Sol-gel - Abstract
Nanocrystalline anatase titania thin films were prepared by using two different precursor solutions, a highly acid solution (Sol-1) and a polymer-like solution (Sol-2), via the dip-coating technique on different substrates (-Si wafer, fused silica and soda lime glass). The influence of the two sol-gel titania precursor solutions and of the substrate type on the film morphology, coating porosity, surface roughness, crystalline phases and grain size of the titania films were investigated. Our experimental results clearly indicate that the sol - composition and substrate type remarkably influence the microstructural/morphological properties of the titanium dioxide. They consequently modify the optical response and hydrophilic performances of the samples. The photocatalytic oxidations of the methylene blue in water of the samples grown on the glass substrate were monitored to investigate the influence of the sol-gel precursor solution on the photocatalytic activity of the titania coatings, and the results were put in relation with the hydrophilic and optical properties of the films. The outcome demonstrates that the optical properties and the hydrophilic and photocatalytic performances of nanocrystalline titania can be opportunely tailored tuning the size dimension of the crystalline domain according to the specific coating applications.
- Published
- 2011
41. A Comparison between Conventional Thermal Treatment and Excimer Laser Irradiation Performed on Alumina/PEEK Composite Coatings
- Author
-
D. Carbone, E. Salernitano, Paolo Rotolo, Gilberto Leggieri, Leander Tapfer, V. Martina, Rossella Giorgi, Anna Paola Caricato, M. Federica de Riccardis, Luciano Pilloni, P.VINCENZINI, G. MONTAVON, M. F., DE RICCARDIS, V., Martina, D., Carbone, P., Rotolo, Caricato, Anna Paola, Leggieri, Gilberto, L., Pilloni, L., Tapfer, R., Giorgi, and E., Salernitano
- Subjects
chemistry.chemical_classification ,Allumina ,Materials science ,Excimer laser ,medicine.medical_treatment ,Composite number ,Polymer ,Thermal treatment ,engineering.material ,Crystallinity ,PEEK ,chemistry ,Coating ,EPD ,Laser treatment ,Melting point ,medicine ,engineering ,Peek ,Composite material - Abstract
Poly(etherether-ketone)-alumina coating were deposited by EPD. In order to densify the coatings, conventional thermal treatments were performed at a temperature equal or higher than the melting point of the polymer. The samples treated at the lower temperature showed an increase in the quality of crystallinity of the polymer. As an alternative method, an excimer laser was used to treat the surface of the composite coatings. The laser beam irradiation did not induce any modification in the crystalline structure of the polymer and at the same time did not produce strong degradation of the polymer molecule, also when the laser beam fluence was higher than the ablation limit. The most relevant modification induced by both the treatments was a change in the morphology and the porosity.
- Published
- 2010
42. Layered silver nanoparticles embedded in a BaF(2) matrix: optical characterization
- Author
-
Luciano Pilloni, Maria Lucia Protopapa, Antonella Rizzo, and Marilena Re
- Subjects
Optics and Photonics ,Materials science ,Silver ,Absorption spectroscopy ,Materials Science (miscellaneous) ,Barium Compounds ,Physics::Optics ,Metal Nanoparticles ,Nanotechnology ,Dielectric ,Industrial and Manufacturing Engineering ,Silver nanoparticle ,Nanoclusters ,Nanomaterials ,Fluorides ,Optics ,Business and International Management ,Surface plasmon resonance ,business.industry ,Surface plasmon ,Equipment Design ,Models, Theoretical ,Surface Plasmon Resonance ,Optical coating ,Optoelectronics ,business - Abstract
Multilayer stacks of silver and BaF(2) alternate layers have been deposited by thermal evaporation on a silica substrate with the aim to obtain Ag clusters dispersed in a BaF(2) insulator matrix. The Ag layer thickness was approximately 1.2 nm; the thickness of the BaF(2) layer was approximately 25 nm. The samples were thermally treated for a 1 h thermal annealing process at 500 degrees C. These kinds of multilayer device also have several applications in the field of optics for the realization of antireflection coatings. However, optical characterization of dielectric matrices that contain layered metallic nanoparticles still remains an unsolved problem in the field of nanostructured optical coatings. Therefore, the surface plasmon resonance peak that appears in the optical absorption spectra because of the formation of Ag nanoclusters inside the BaF(2) insulator matrix has been monitored and fitted by numerical codes. In particular, a previously published theoretical model, based on the Maxwell-Garnett effective medium theory, modified to take into account the effects that are due to the particle shapes and the spatial arrangement of the clusters, has been employed to fit the optical absorption spectra.
- Published
- 2009
43. Metallographic characterization of MgH2-Mg system
- Author
-
Amelia Montone, Luciano Pilloni, M. Vittori Antisari, D. Mirabile Gattia, Annalisa Aurora, and M. R. Mancini
- Subjects
chemistry.chemical_compound ,Hydrogen storage ,Materials science ,chemistry ,Magnesium ,Desorption ,Microscopy ,Magnesium hydride ,Inorganic chemistry ,Solid-state ,chemistry.chemical_element ,Hydrogen desorption ,Characterization (materials science) - Abstract
Magnesium represents an important candidate for solid state hydrogen storage even if the hydrogen desorption temperature is too high for most applications.
- Published
- 2009
44. Development of SEM Metallography for the Study of the Mg-MgH2 Phase Transformation
- Author
-
Annalisa Aurora, Rita Mancini, Marco Vittori Antisari, Amelia Montone, Daniele Mirabile Gattia, Nadica D. Abazović, Milica Drvendzija, and Luciano Pilloni
- Subjects
Matrix (chemical analysis) ,Metal ,Hydrogen storage ,Materials science ,Chemical engineering ,Phase (matter) ,visual_art ,Metallography ,visual_art.visual_art_medium ,Sorption ,Absorption (chemistry) ,Decomposition - Abstract
The study of sorption reactions of metal hydrides is the subject of numerous researches in connection with the development of a safe technology for hydrogen storage, and MgH2, in particular, is one of the most promising materials. Several efforts have been already carried out in order to understand the kinetic mechanisms involved in the MgH2 decomposition which is at the basis of H2 release. However, the role of additives and induced structural defects on the sorption cycles is not clear yet. With the purpose of supporting the reaction analysis we have developed an experimental protocol for the metallographic examination at high spatial resolution of partially desorbed MgH2 powders. In particular, this procedure allows cross-sectional analysis of powders embedded into conductive matrix, while the observation method produces a different contrast among metallic Mg, MgH2 and additive particles made of heavier materials.
- Published
- 2007
45. A comparative study about the hydrogen embrittlement susceptibility of Eurofer'97 and conventional 9%cr ferritic/martensitic steels
- Author
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G. Filacchioni, Luciano Pilloni, and Marie-Françoise Maday
- Subjects
Materials science ,Hydrogen ,chemistry ,Martensite ,Metallurgy ,Hardening (metallurgy) ,chemistry.chemical_element ,Grain boundary ,Fractography ,Hydrogen content ,Embrittlement ,Hydrogen embrittlement - Abstract
Constant displacement rate tests have been performed in conjunction with the electrochemical hydrogen charging technique to evaluate the relative susceptibility to hydrogen embrittlement of the martensitic steels: Eurofer'97, T91 and EM10. Mechanical property and failure mode results associated with any specific hydrogenation condition were fairly reproducible in the conventional alloys, showing a minor tendency to hardening and a major resistance to embrittlement effect at high hydrogen content of T91 compared to EM10. The underlying mechanism for damage could be identified and tentatively explained, based on fractographic evidences and microstructural arguments. Conversely, the results of replicated tests on Eurofer were significantly scattered and gave rise to embrittlement behaviours fitting those of either T91 or EM10, probably due to local heterogeneity of grain boundary chemistry.
- Published
- 2006
46. Low energy pure shear milling: A method for the preparation of graphite nano-sheets
- Author
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Emanuela Piscopiello, C. Alvani, Luciano Pilloni, M. Vittori Antisari, N. Jovic, and Amelia Montone
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Materials science ,Mineralogy ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Stress (mechanics) ,Condensed Matter::Materials Science ,Powder metallurgy ,transmission electron microscopy (TEM) ,General Materials Science ,Graphite ,Composite material ,Lubricant ,mechanical milling ,Mechanical Engineering ,Metals and Alloys ,Pure shear ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,0104 chemical sciences ,Grinding ,Shear (sheet metal) ,Mechanics of Materials ,carbon and graphite ,nano-crystalline materials ,0210 nano-technology ,grain refining - Abstract
Graphite nano-sheets, having a thickness of the order of 10 nm, high shape asymmetry, and a well preserved crystalline order, have been prepared by a mechanical method based on the grinding of graphite powder under low energy pure shear milling using water as a lubricant. The small applied stress activates the plastic deformation process mainly on the easy gliding (00 1) hexagonal planes so that planar flakes bounded by the basal planes are obtained by a purely mechanical process. (c) 2006 Published by Elsevier Ltd. on behalf of Acta Materialia Inc.
- Published
- 2006
47. Intermediate Temperature Bend Strength of 5 Weight % Yttria Stabilized Zirconia
- Author
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A. Moreno, Luciano Pilloni, G. Filacchioni, E. Casagrande, U. De Angelis, and D. Ferrara
- Subjects
Fabrication ,Reliability (semiconductor) ,Materials science ,Flexural strength ,Weibull modulus ,visual_art ,visual_art.visual_art_medium ,Modulus ,Cubic zirconia ,Ceramic ,Composite material ,Yttria-stabilized zirconia - Abstract
A ceramic fabrication, characterisation and mechanical property evaluation procedure has been established. Reliability has been demonstrated for partially stabilized zirconia: satisfactory strength and Young’s modulus data have been obtained at ambient temperature and at 850°C.
- Published
- 1991
48. Growth, characterization and optical properties of nanocrystalline gadolinia thin films prepared by sol–gel dip coating
- Author
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Luciano Pilloni, Maria Cristina Ferrara, Enrico Nichelatti, Leander Tapfer, D Altamura, Monica Schioppa, and M Montecchi
- Subjects
Materials science ,Thin layers ,Acoustics and Ultrasonics ,Absorption spectroscopy ,Silicon ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,Dip-coating ,Nanocrystalline material ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Surface coating ,chemistry ,Thin film ,Fourier transform infrared spectroscopy - Abstract
Nanostructured gadolinia thin layers with small sized crystalline grains (∅ ≈ 3–13 nm) were successfully prepared by the sol–gel process on fused silica and silicon substrates. The film growth, the chemical composition, the morphology and the microstructure of the films were investigated in detail by thermo-gravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and x-ray diffraction. The experimental results clearly show that the morphological and structural properties of the films are not influenced by the substrate properties and the Gd2O3 cubic crystalline phase (symmetry group ) is enhanced when the films are free from organic residuals and decompose to Gd-oxides. FTIR analysis of gadolinia layers grown on silicon suggest that the formation of Gd2O3 grains may favour the diffusion of oxygen through the coatings. The optical spectroscopy measurements evidence a blue shift of the energy gap and suggest a quantum confinement effect in nano-sized Gd2O3. In addition, two absorption features are observed, which can be attributed to a simultaneous presence of direct and indirect electronic transition indicating a modification of the band structure when the grain size changes from very small to larger Gd2O3 grains.
- Published
- 2008
49. Electron Microscopy study of nanocrystalline wurtzite ZnS produced via a co-precipitation technique and its pyroelectric ceramics processed by 2-step- pressureless sintering
- Author
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Radenka Krsmanovic Whiffen, Loris Pietrelli, Luciano Pilloni, Giuseppe Magnani, Elena Salernitano, Selene Grilli, Francesca Mazzanti, and Amelia Montone
- Subjects
7. Clean energy - Abstract
The pyroelectric performances of non-ferroelectric pyroelectrics like wurtzite- based materials (e.g. AlN, GaN, CdS or ZnO) make them important, although not widely used, compared to the current state-of-the-artferroelectrics. Their high chemical and thermal stability allows their use at high temperatures in air, whereas ferroelectrics become ineffective when heated beyond their Curie temperature (TC). Wurtzite based materials have ahigher thermal conductivityallowing them to react faster to ambient temperature changes, their raw materialcosts are lowerand many of them areeco-friendly. Current pyroelectrics applications are limited to portable systems or tasks needing only μW–mW power. To be commercially viable, we must improve the current low efficiency of pyroelectric systems and intrinsically enhance the pyroelectric properties of modern materials through suitable doping or material engineering. We chose to study hexagonal wurtzite phase of ZnS, among the structurally simplest of pyroelectrics, as a possible energy harvesting material. An easy synthesis method – a co-precipitation technique, was tailored for nanocrystalline wurtzite ZnS production. This method is easy to scale-up and our next step is to build an in-house pilot plant that will produce substantial amounts of wurtzite ZnS nano-powder in an environmentally friendly and cost-effective manner. We further investigated the development of bulk, dense pyroelectric ceramics by the Two-Step Sintering (TSS) fabrication process, using as the precursor material both a micron-sized commercial powder of the ZnS cubic and hexagonal phases mixture, and an in-house produced wurtzite ZnS nanopowder. The TSS was chosen as being a pressureless, simple and cost‐effective sintering method for obtaining high density materials with controlled grain growth operating at a lower temperature than the conventiona process. Electron Microscopy techniques helped us to study the microstructure and morphology of both the precursor nanopowders and the obtained ceramics. Acknowledgement: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 797951.
50. Orthopaedic implant corrosion. General aspects | La corrosione degli impianti in ortopedia: Caratteristiche generali ed aspetti macroscopici
- Author
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Maccauro, G., Nizegorodcew, T., Lorini, G., Luciano Pilloni, and Santis, E.
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