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Particle stabilized liquid foams are used as templates to obtain carbon-based porous materials with open cell structure, high specific area and hierarchical porosity. This route relies on gel casting to strengthen the structure of the liquid foams, followed by high temperature treatment to eliminate organic components and obtain solid foams. The liquid foam stabilizer was a commercial activated carbon powder, characterized by high porosity and irregular morphology of the particles, associated with a cationic surfactant. The micro-structure and the textural properties of the final solid materials have been investigated by Scanning Electronic Microscopy and Nitrogen adsorption methods. The results show that this method can be used to fabricate high specific area porous materials in the form of monoliths, with adequate consistence and mechanical resistance. The materials obtained seem promising for many practical applications such as gas adsorption, filtering and catalysis.

The thermodynamic properties of liquid In-Sn alloys indicate a weak interactions between unlike atoms. The new In, Sn and In-Sn surface tension experimental data set obtained by the large-drop method over the temperature range 523-923 K together with the literature data on different thermophysical properties substantiate a nearly ideal mixing behaviour of these alloys. A low interaction energies do not effect the composition dependence of thermophysical properties, in particular the surface tension and the surface segregation. In order to estimate the effects of the short-range order phenomenon on the surface properties of In-Sn liquids, the QCA (quasi chemical approximation) for the regular solution model and the CFM (compound formation model) have been applied. In the same framework the transport properties and the structural characteristics of liquid In-Sn alloys have also been analysed.

La presente attività di ricerca si inserisce nell'ambito del progetto ESA "OXYTHERM" (AO-2009-1136) con l'obiettivo di preparare e supportare gli esperimenti che saranno condotti sulla facility sperimentale MSL-EML nella stazione spaziale internazionale. Tali esperimenti hanno lo scopo condotti allo scopo di valutare, anche in condizioni di microgravità, l'influenza della pressione parziale di ossigeno e delle condizioni fluidodinamiche dei processi di trasporto tra fase gas e fase liquida, sulla tensione superficiale e altre proprietà termo fisiche di leghe binarie e sistemi più complessi di interesse industriale. I risultati ottenuti saranno di utilità per l'ottimizzazione dei processi tecnologici quali saldatura, processi di giunzione, casting, crescita di monocristalli, produzione di materiali compositi e schiume metalliche. Nonostante la fenomenologia dei processi di interazione con ossigeno siano a livello industriale così determinanti nell'ottenere un prodotto finale di elevata qualità ed esente da difetti, la letteratura a disposizione e' carente e poco contribuisce a chiarire sopratutto i meccanismi di interazione (adsorbimento e formazione di fasi di ossido stabile) e trasporto all'interfaccia metallo liquido-atmosfera. Per questo motivo, la ricerca qui presentata focalizza il suo programma e la sua attività nello studiare, tramite un approccio combinato teorico-sperimentale, il comportamento di alcuni sistemi binari scelti come sistemi modello (Ag-Cu e Cu-Sn) nei confronti di atmosfere più o meno ossidanti. La campagna sperimentale di supporto a terra, è stata organizzata seguendo uno studio sistematico dei parametri operativi in un ampio intervallo di composizione e temperatura. Le misure di tensione superficiale sono state eseguite su metalli puri e leghe binarie sia in condizioni riducenti, sia in condizioni di ossidazione controllata.

Corrosion behaviour of ferritic and ferritic-martensitic oxide dispersed strengthened (ODS) steels woth different chromium content (9, 12 and 14 % Cr) have been tested in stagnant liquid lead with an oxygen concentration cO2 = 10-6 wt%. The study has been carried out with the aim to identify the most appropriate structural materials for advanced nuclear energy system and waste transmutation system. [...]

In the framework of OXYTHERM ESA-MAP Project, a systematic study of oxygen influence on molten Ag-Cu alloys, taken as binary model system, was performed. The project is aimed to the development of improved physico-chemical models providing a deeper understanding of the basic interaction mechanisms of oxygen on liquid alloys and on the influence on their thermophysical properties such as surface tension, viscosity, and density. It exploits measurements performed on board of the ISS by using MSL-EML facility equipped with the Oxygen Sensing and Control device (OSC), in order to obtain information will serve as a benchmark for the quality of ground based experiments. In this work, the interactions between Ag-Cu molten alloys and an oxidising atmosphere are theoretically approached by applying different models: a thermodynamic Belton's like model [1], which allows the adsorption isotherms to be evaluated and a fluid dynamic model [2], which allows to determine the boundary separating oxidation and de-oxidation regimes, for the liquid alloys surface. The models have been validated by surface tension data measured as a function of oxygen partial pressure in two different apparatuses by using a containerless- and a container- based technique, respectively. The former is very similar to the device, named TEMPUS, designed by DLR, that is used on the ISS for the microgravity measurements. In this apparatus the surface tension was measured by oscillating drop method using electromagnetic levitation (EML) over a wide range of temperatures above the melting point and under oxygen control (OSC)[3]. In the other one, dynamic surface tension measurements [4] have been performed by the large drop method in order to study the evolution of the molten alloy surface in the presence of traces amount of oxygen. Such measurements are out of equilibrium and they can provide information about the kinetics and the mechanisms of mass transfer to and through the surface. [1] R. Novakovic R., D. Giuranno, E. Ricci, Molten 2009 Proceeding article n. cap. 02 ( 2009) 70. [2] E. Arato, M. Bernardi, D. Giuranno, E. Ricci, Applied Surface Sci. 258 (2012) 2686. [3]M. Schulz, J. Brillo, C.Stenzel, H. Fritze , Solid State Ionics 225 (2012) 332. [4] E. Ricci, E. Arato, A. Passerone, P. Costa, Advance of Colloid and Interface Science 117 (2005) Acknowledgements: This work was performed in the framework of the European Space Agency (ESA) Microgravity Applications Support Programme (MAP) and supported by the Italian Space Agency (ASI) under contract DC-MIC-2011-036 "OXYTHERM".

Thermophysical properties of liquid Co-Si alloys are interesting for composite materials production. However, despite the importance of these properties, the determination of their thermophysical properties is lacking due to the experimental difficulties related to high melting temperatures as well as due to the high reactivity of these alloys with crucible materials. The energetics of mixing in liquid Co-Si system has been analyzed through the study of the concentration dependence of various thermodynamic, surface (surface tension and surface composition) and structural properties (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of the Compound Formation Model (CFM) and Quasi Chemical Approximation for regular solutions (QCA). The surface tension of a few Co-Si liquid alloys has been measured as a function of temperature above the corresponding liquidus temperatures. The results obtained were discussed with respect to both, temperature and concentration, and subsequently were compared with the aforementioned thermodynamic models.

The applicability of quasi-lattice theory (QLT) to describe surface and transport properties of Ag-Cu liquid alloys is substantiated by surface tension experimental data. The surface tension of molten Ag, Cu and Ag-Cu alloys has been measured by the pinned-sessile drop method over a temperature range. The results obtained are in good agreement with other reported measurements on pure elements and their alloys as well as with calculated surface tension values. The phase diagram of Ag-Cu system shows the existence of a simple eutectic indicating a tendency towards phase separation. The mixing behaviour of Ag-Cu regular alloys has been analysed through the study of surface properties (surface tension and surface composition), dynamic properties (chemical diffusion and viscosity) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the frame of quasi-lattice theory combined with a statistical mechanical theory.

The present work is an experimentally based investigation of the applicability of the complex formation model (CFM) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory (QLT) to describe the surface and transport properties of Au–Sn liquid alloys. Depending on melting temperatures, the surface tension of molten Au and Au–Sn alloys has been measured by the pinned-large drop method in the temperature range of T = 1275–1493 K. The calculations have been done with various objectives in view, i.e., to analyse existing thermodynamic data related to the peculiarities of the Au–Sn phase diagram, to use these data as the input for the interaction parameter calculations, to calculate the surface properties (surface tension and surface composition) and to compare the computed data with a new set of the surface tension experimental data as well as to predict the values of dynamic properties (chemical diffusion and viscosity). Some information on the structure of Au–Sn liquid alloys are given in terms of the microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter).