1,721,014 research outputs found
A simple route for additive manufacturing of 316L stainless steel via Fused Filament Fabrication
No full textCorrosione di materiali compositi a matrice metallica MMC con rinforzo ceramico
Full text linkI materiali compositi a matrice metallica (MMC) sono materiali avanzati con elevate proprietà fisiche emeccaniche. In questo lavoro vengono studiati e messi a confronto il comportamento a corrosione di duetipologie di MMC con matrice in alluminio e rinforzo particellare in allumina. I dati ottenuti con le proveelettrochimiche, eseguite immergendo i provini in soluzione 3.5% NaCl, mostrano come la corrosione negliMMC sia influenzata sia dalla presenza delle particelle di allumina ma soprattutto dai composti intermetallicipresenti nella matrice che risultano essere i siti preferenziali di innesco della corrosione per pitting
PEEK -TiO2 composites with enhanced UV resistance
No full textIn the paper, extruded filaments of polyetheretherketone (PEEK) filled (1%v, 3%v, 5%v) with sub-micrometric titanium dioxide (TiO2) particles have been manufactured with the aim to increase the UV radiation resistance of PEEK matrix. The TiO2 particles affect crystallinity of PEEK matrix as it increases increasing filler content. The filler presence slightly increases the stiffness and the elastic modulus of resulting composites and does not influence largely the tensile strength but show an influence on the elongation at break enhancing a finger like failure mechanism ascribed to microcracks propagation and interspherulitc fracture. UV aging test showed the effectiveness of TiO2 particles in reducing the photo-degradation effect especially in 5%v filled sample resulting the most effective formulation. For this formulation, after UV aging the mechanical properties and the failure mechanism remains unchanged while the neat PEEK sample shows embrittlement and loss of ductility
L'empatia etnoculturale e la sua relazione con il pregiudizio: contributo alla validazione italiana della scale of Ethnocultural Empathy
No full textThe present study examined the validity of the Scale of Ethnocultural Empathy (SEE), (Wang et al., 2003), and found further evidence for the scale’s good psychometric properties. The SEE was administered to a sample of 124 Italian psychology students to examine the generalizability and reliability of its factor structure. The results of the confirmatory factor analysis showed a reasonable data fit with the SEE’s hypothesized four domains (i.e. Empathic Feeling and Expression, Empathic Perspective Taking, Acceptance of Cultural Differences, and Empathic Awareness). Scale reliability was also satisfactory, showing good internal consistency. Lastly, high SEE scores were significantly associated with low levels of prejudice. Cultural differences between the U.S and Italian SEE versions, research and practice implications are discussed
Corrosion behavior of AI<inf>2</inf>O<inf>3</inf>/Al metal matrix composites (MMC)|Corrosione di materiali compositi a matrice metallica MMC con rinforzo ceramic
No full textI materiali compositi a matrice metallica (MMC) sono materiali avanzati con elevate proprietà fisiche e meccaniche. In questo lavoro vengono studiati e messi a confronto il comportamento a corrosione di due tipologie di MMC con matrice in alluminio e rinforzo particellare in allumina. I dati ottenuti con le prove elettrochimiche, eseguite immergendo i provini in soluzione 3.5% NaCl, mostrano come la corrosione negli MMC sia influenzata sia dalla presenza delle particelle di allumina ma soprattutto dai composti intermetallici presenti nella matrice che risultano essere i siti preferenziali di innesco della corrosione per pitting
Influence of organic modified silica coatings on the tribological properties of elastomeric compounds
No full textThe frictional behaviour of elastomers has attracted a lot of attention and interest in order to better comprehend its effect on the skidding features of tires and the performance of different rubber components, such as gloves, contact rubber seals and diaphragms, and elements of weapons.In the present work, for the first time, silica coatings were deposited on the surface of different elastomeric compounds (i.e. butadiene rubber (BR), styrene-butadiene rubber (SBR) and silica loaded butadiene rubber (BRs)) by dip-coating technique, with the aim to modify their surface properties, leading to a decrement of the friction coefficient. A green sol-gel methodology was exploited, avoiding the use of toxic chemical substances. The influence of the silica coating on the surface properties of the elastomeric compounds was deeply investigated by means of scanning electron microscopy (SEM), static contact angle measurements and tribological tests. The obtained coatings were characterised by an average thickness of around 1-2 mu m, flexibility, due to the presence of cracks, developed during the drying process, a very good adhesion to the elastomeric substrates in the case of thinner coatings (1 dip-samples). Moreover, they provided an enhanced hydrophobic behaviour, lower surface free energies and lower friction coefficient values (friction coefficient decrease up to 30%)
Silver electroless plating on 3D printed resins via stereolithography: A sustainable solution
No full textWaste cooking oils as processing aids for eco-sustainable elastomeric compounding
No full textThis work focuses on the replacement of mineral oils with bio-based waste cooking oils in rubber compounding. Two different waste cooking oils from potatoes and chicken frying process were analyzed by means of chemical and rheological tests to evaluate the chemical composition, the oxidative stability and the viscosity. Waste oils have been introduced in elastomeric compounds as substitute for typical processing aids (i.e. lubricants). Cure kinetics of rubber compounds was studied by rheological characterization. Mechanical properties of vulcanized samples were determined by means of tensile tests, hardness tests and dynamic mechanical analysis. The waste oils showed a rheological behavior very similar to the mineral oils conventionally employed in rubber manufacturing leading to almost the same processability of the resulting compound. The waste oils did not significantly affect the vulcanization kinetics of the rubber compound, as expected for conventional lubricants. Waste cooking oils and mineral oil show analogous influence on mechanical properties of cured compounds. At increasing oil content, the elongation at break and the tensile strength increased whereas the values of Elastic Modulus at 100% strain, the Storage Modulus and Shore A Hardness decreased with respect to the oil-free sample. These results are very promising, confirming the possibility to replace the mineral oils, in a good practice of circular economy
Fused Filament Fabrication of Alumina/Polymer Filaments for Obtaining Ceramic Parts after Debinding and Sintering Processes
No full textSelf-Monitoring Performance of 3D-Printed Poly-Ether-Ether-Ketone Carbon Nanotube Composites
No full textIn this paper, poly-ether-ether-ketone (PEEK) carbon-nanotube (CNT) self-monitoring composites at different levels of filler loading (i.e., 3, 5 and 10% by weight) have been extruded as 3D-printable filaments, showing gauge factor values of 14.5, 3.36 and 1.99, respectively. CNT composite filaments of 3 and 5 wt% were 3D-printed into tensile samples, while the PEEK 10CNT filament was found to be barely printable. The 3D-printed PEEK 3CNT and PEEK 5CNT composites presented piezo-resistive behavior, with an increase in electrical resistance under mechanical stress, and showed an average gauge factor of 4.46 and 2.03, respectively. Mechanical tests highlighted that 3D-printed samples have a laminate-like behavior, presenting ultimate tensile strength that is always higher than 60 MPa, hence they offer the possibility to detect damages in an orthogonal direction to the applied load wit high sensitivity
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