1,721,173 research outputs found
A Continuous 3D-Graphene Network to Overcome Threshold Issues and Contact Resistance in Thermally Conductive Graphene Nanocomposites
Full text linkEffect of Graphene Nanoplatelets (GNPs) on Properties of Pure Copper
No full textGraphene nanoplatelets (GNPs)/copper composites has been prepared by conventional powder metallurgy. Although GNPs/Al composites are widely studied, homogeneous dispersion of GNPs is still a big challenge for the researchers, which limits its use in practical applications. Our novel nano-processing route is free of ball milling which can damage the structure of GNPs during mixing. Therefore, our method can be an alternative of ball milling and it has a great potential for the synthesis of Cu based matrix nano-composite which is considered good for engineering applications. Nevertheless, the interface of GNPs/Cu plays a critical role in electrical resistivity in such a way that by increasing the GNPs/Cu interface the electrical resistivity increased.Nonetheless the hardness of the composite was increase by the introduction of GNPs
Effect of oxidation of end-of-life tire rubber as aggregate substitute in cement mortars
Full text linkIn this paper the possible use of end-of-life tire rubber as a substitute for aggregate in cement mortars was explored. The aim of this paper was to investigate the effect of rubber surface modification by acidic treatment on the final properties of mortars. In fact, through treatment with sulfuric acid at moderate concentrations, a significant improvement in rubber wettability and interaction with cement has been observed. The compressive strength of mortars containing 15%w treated rubber as a replacement of natural aggregate is comparable to those of standard mortars. This suggests that surface modification of rubber plays a very important role in the possible integration of end-of-life tire rubber in mortar and concrete. The results presented in this paper confirm that recycling in mortar and concrete is a promising way for improving rubber waste management and sustainable innovation in the construction industry
A continuous 3D-graphene network to overcome threshold issues and contact resistance in thermally conductive graphene nanocomposites
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Al(Si)/Al2O3 and NiAl(Si)/Al2O3 co-continuous composites obtained by low temperature reactive metal penetration of dense silica preforms
Full text linkInterpenetrating network Al(Si)/Al2O3 composites, obtained by a reactive metal penetration process, where pure aluminum metal reacts with a dense amorphous silica preform, are an interesting class of metal/ceramic composites, with two continuous networks of metal (Al-Si alloy) and ceramic (Al2O3). These composites have high stiffness and hardness, while retaining acceptable toughness and good thermal and electrical conductivity, and can be used in wear or thermal management applications. A second infiltration step with nickel allows to substitute the Al(Si) alloy with an intermetallic, obtaining an interpenetrating network NiAl(Si)/Al2O3 composite, with very high hardness and melting point. While in the standard process the temperature for obtaining the Al(Si)/Al2O3 composites is in the 1100–1200 °C range, in this paper we studied instead the 700–1000 °C temperature range and its effect on the microstructure of the final NiAl(Si)/Al2O3 composite. After the first infiltration step, the microstructure of Al(Si)/Al2O3 composites depends on both temperature and time of the treatment. At 700–800 °C and for reaction time of 1–2 h, the grain size is completely sub-micrometric. When temperature and time of reaction increase, islands with a coarser microstructure, of micrometric size, form, reaching a fully micrometric coarser microstructure at 1100–1200 °C. The islands formation is due to the transformation from transition aluminas, formed at low temperature and low reaction time, to α-alumina, while at high temperature α-alumina forms directly. In a second step, the Al(Si) metal network was replaced with an intermetallic one, by contacting the composite with liquid nickel, that reacted with the Al(Si) alloy forming an Al-Ni-Si intermetallic. The temperature and duration of the first infiltration step strongly influences not only the microstructure of the Al(Si)/Al2O3 composite but also of the final NiAl(Si)/Al2O3 one, that is finer when the first step (reaction of aluminum with silica) occurs at lower temperature
Piezoresistive cement nanocomposites
No full textMethods may include pumping a cement composition containing one or more conductive fillers into an annular region of a wellbore created between a casing and a surface of the wellbore, allowing the cement composition to cure, emplacing a tool for measuring at least one electromagnetic property into the wellbore, and measuring at least one of the cemented casing and the formation. In another aspect, methods may include preparing a cement composition containing one or more conductive fillers, allowing the cement composition to set, and measuring at least one electromagnetic property of the set cement. In yet another aspect, cement compositions may contain a cement, one or more conductive fillers, and a surfactant, wherein the resistivity of the cement composition is less than 10 Ω*
Hydrophobic cellulose ester as a sustainable material for simple and efficient water purification processes from fatty oils contamination
No full textIn this study, cellulose fibers were chemically functionalized under mild conditions by introducing palmitate groups in order to produce a hydrophobic cellulose-based ester. The effectiveness and the degree of functionalization were evaluated by FTIR spectroscopy and thermogravimetric analysis, whereas the structural integrity was confirmed by XRD measurements. The prepared materials were tested in water remediation processes from fatty oils mixtures from both animal (cod liver oil) and vegetable (sunflower oil) sources. Experimental kinetic measurements, rationalized by means of the most common models, show that the best performances were reached toward the sunflower oil, hence proving the promising application of such green materials as a sustainable alternative tool for oil–water remediation processes
Processing of co-continuous ceramic composites by reactive penetration method: influence of composition of ceramic preforms and infiltrating alloys
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