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23 results on '"F. Carassiti"'

1. High-resolution high-speed nanoindentation mapping of cement pastes: Unravelling the effect of microstructure on the mechanical properties of hydrated phases

Author

F. Carassiti, Piero Baglioni, Riccardo Moscatelli, Francesca Ridi, Marco Sebastiani, Sebastiani, Marco, Moscatelli, Riccardo, Ridi, F., Baglioni, P., and Carassiti, Fabio

Subjects
Work (thermodynamics), Materials science, Cement, 0211 other engineering and technologies, 02 engineering and technology, Nanoindentation, 021105 building & construction, lcsh:TA401-492, Mechanics of Material, General Materials Science, Soft matter, Composite material, Packing density, Mechanical Engineering, Statistical, High-speed, 021001 nanoscience & nanotechnology, Microstructure, Strength of materials, Sphere packing, Mapping, Mechanics of Materials, lcsh:Materials of engineering and construction. Mechanics of materials, Materials Science (all), Cementitious, 0210 nano-technology
Abstract

Cementitious materials represent the most used materials in the construction industry. Their strong heterogeneity and multiscale microstructure make the study of the mechanical properties and the in-service behaviour very challenging: new techniques are required by industrial research to better investigate these aspects. In this work a novel technique based on statistical nanoindentation is exploited to obtain results about the microstructure build-up and the mechanical properties. An innovative high-speed nanoindentation method is here combined and compared with a standard nanoindentation procedure in order to get highly consistent statistical results. Combining the high-speed nanoindentation, the statistical deconvolution and SEM/EDS investigations, the main phases present in the tested hydrated cement paste have been characterized. High-resolution maps of the mechanical properties are in good agreement with SEM-EDS results. The evolution of the mechanical properties has been tested over the time and in particular after 1, 3, 5, 7, 14 and 28 days of hydration. It was found that the nano-mechanical properties were almost constant during the hydration time and the evolution of the bulk mechanical resistance properties of the cement paste is found to be due to a variation of the volume proportions between the three principal phases (low-density, high-density and ultra-high-density C–S–H). Keywords: Cement, Nanoindentation, High-speed, Statistical, Mapping, Packing density

Published
2016

2. Different Sputtering Configurations For Coating 1,5 Ghz Copper Cavities

Author

G. LANZA, V. PALMIERI, N. PATRON, C. PIRA, S. STARK, F. CARASSITI, SEBASTIANI, MARCO, H. PADAMSEE, BEMPORAD, Edoardo, Carassiti, Fabio, G., Lanza, V., Palmieri, N., Patron, C., Pira, S., Stark, Bemporad, E, M, Sebastiani, H., Padamsee, Lanza, G, Palmieri, V, Patron, N, Pira, C, Stark, S, Carassiti, F, Sebastiani, Marco, Padamsee, H., Bemporad, Edoardo, and F., Carassiti

Published
2007

8. Load bearing capacity and failure modes analysis of PVD/HVOF duplex coatings

Author

Edoardo Bemporad, Marco Sebastiani, F. Carassiti, Alberto D'Amore, Bemporad, Edoardo, Sebastiani, Marco, Carassiti, Fabio, D. ACIERNO, A. D'AMORE, D. CAPUTO, R. CIOFFI, Carassiti, F., Bemporad, E, and D. ACIERNO, A. D'AMORE, D. CAPUTO AND R. CIOFFI

Subjects
Materials science, business.industry, Duplex (telecommunications), Structural engineering, Composite material, business, Thermal spraying, Load bearing
Published
2009

9. Production and characterization of duplex coatings (HVOF and PVD) on Ti-6Al-4V substrate

Author

Marco Sebastiani, Daniele De Felicis, Edoardo Bemporad, R. Valle, F. Casadei, F. Carassiti, Bemporad, Edoardo, Sebastiani, Marco, De Felicis, D, Carassiti, F, Valle, R, Casadei, F., Bemporad, E, DE FELICIS, D, Casadei, F, Carassiti, F., D., DE FELICIS, Carassiti, Fabio, R., Valle, F., Casadei, aa. vv., and DE FELICIS, Daniele

Subjects
Toughness, Materials science, Scanning electron microscope, Composite number, Metallurgy, Metals and Alloys, Surfaces and Interfaces, engineering.material, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Duplex system, PVD, Contact mechanics, Coating, Residual stress, Indentation, Materials Chemistry, engineering, HVOF, Thermal spraying
Abstract

Present paper deals with modelling, production and characterization of HVOF PVD (WC-Co and TiN or CrN, respectively) duplex coatings deposited on Ti-6Al-4V substrate for application in automotive industry. As a preliminary analysis, an analytical study of the contact stress distribution under spherical indenter in both coated and uncoated systems, and a finite element evaluation of residual stresses were performed: results showed that the presence of an interlayer with intermediate hardness and stiffness (such as the WC-Co coating) plays a fundamental role in the improvement of the load carrying capacity. Starting from the results of simulations, morphological and compositional characterization of the coatings were performed using SEM and AFM techniques. Mechanical properties were investigated by micro indentation techniques and composite hardness modelling; toughness of the system was qualitatively analysed by Rockwell C indentation. Wear rate of the coatings was measured by an implemented rotating wheel method. Results show higher superficial composite hardness, toughness, adhesion and lower wear rate, in comparison with the simple monolayer system. (c) 2005 Elsevier B.V. All rights reserved.

Published
2006

12. Rapid solidification of plasma sprayed advanced materials: nanostructure characterisation

Author

F. Carassiti, Edoardo Bemporad, Cecilia Bartuli, Teodoro Valente, Bartuli, C, Valente, T, Bemporad, Edoardo, and Carassiti, F.

Subjects
Inert, plasma spray, Materials science, Nanostructure, nanostructure, eutectic, Mechanical Engineering, Composite number, sad, zrb2-sic, caps, tem, thermal protection system, Industrial and Manufacturing Engineering, Characterization (materials science), Amorphous solid, chemistry.chemical_compound, chemistry, Mechanics of Materials, Silicon carbide, Composite material, Safety, Risk, Reliability and Quality, Thermal spraying, Eutectic system
Abstract

Composite ZrB2-SiC materials offer well known resistance to ablation at high temperature. An inert plasma spraying technique was used to manufacture composite ZrB2-SiC as potential thermal protection systems for composite based substrates. Due to the rapid solidification experienced by sprayed droplets, amorphous and/or nanostructured phases can be formed; advanced characterization techniques are therefore required in order to collect all the necessary data for process/product optimisation. In addition, silicon carbide, selected for its contribution to the oxidation resistance of the ceramic coating, is well known to be considered as a non sprayable material, due to the lack of a stable liquid phase. In this paper, two issues are investigated: the first is the use of advanced characterization techniques, such as high resolution scanning and transmission electron microscopy, for microstructural analysis of plasma sprayed coatings. The second is the evaluation of possible implications of rapid solidification processes in composite systems for which at least one liquid phase is not stable, but, at the same time, the development of eutectic-like structures results in the formation of nanostructured stable solid phases.

Published
2004

23. Verification of Layered Structures in SnO2/Metal-based Gas Sensors by X-ray Microanalysis: Comparison with X-ray Photoelectron Spectroscopy.

Author

Bemporad E, Carassiti F, Kaciulis S, and Mattogno G

Abstract

The depth profile of thin film layers on bulk substrate, avoiding the cross-sectioning of samples, is commonly performed by techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectroscopy (SIMS). Techniques based on X-ray emission intensity measurements by energy dispersive spectroscopy (EDS), with conventional matrix or ZAF correction, are normally applied to cross-sectioned samples. This article compares XPS with surface X-ray intensity measurements by EDS, carried out with a more realistic X-ray generation and absorption model, known as the pi(rho Z) model. The pi(rho Z) approach has been adopted together with Monte Carlo simulation for the proper selection of SEM accelerating voltages, in conjunction with the analysis of SEM morphological images for thin film density correction. The method discussed hereafter and compared with the XPS technique, has advantages of higher lateral resolution, non-destructive elemental analyses, morphological visualization, low cost, and faster performance. This methodology has been followed to verify the layered structure of SnO2/metal-based gas sensors. X-ray intensities were measured using an EDS ultra-thin window detector. Two different porous layers, 25-nm thick of SnO2 and 10-nm thick of Cu, were detected, showing better agreement with their nominal thickness compared to results obtained using XPS measurements where porosity affects XPS data. If confirmed to be reliable and as effective as XPS depth profiling, this technique may be adopted for process quality control purposes.

Published
2001
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