1,720,975 research outputs found
Life cycle assessment of a sintered tile containing copper slag: is recycling always convenient?
No full textCopper production causes environmental problems related to copper slag disposal. Within this experimental work, copper slag have been used as secondary raw material for the production of sintered tiles, which potential environmental impact was assessed through the Life Cycle Assessment methodology
On a solar reflective ceramic based glaze for asphalt shingle
No full textSolar reflective materials are one of the most effective solutions to counteract Urban Heat Island effect. Among them, asphalt shingles are one of the most widely used products. To improve solar reflectance of these surfaces usually both polymeric paint on the final product or ceramic glazes applied directly on the granules surface through rotary kiln are used. In this study the Design of Experiment approach is applied to an industrial formulation for ceramic glaze for asphalt shingles in order to find the optimal combination between pigment (Rutile and Talc), liquid phase (Sodium Silicate and Water) and heat treatment (700 °C â1100 °C). On the most significant samples, moreover, XRD and ESEM characterization has been performed in order to better understand the behaviour of the studied system. Interesting values in Solar reflectance were obtained, reaching Ïsol=0.882 creating a good solar reflective product ready to be applied, through rotary kiln, on mineral granules for asphalt shingles
Electrical and Structural Characteristic of Copper Oxide (I) Containing Lithium Phosphate Glasses
No full textOxide glasses containing transition metal ions are of enhanced interest because of their applications in information storage, electrical and optical switching devices. The aim of the present work is to design, fabricate and characterize semiconducting glasses containing copper oxide. In such glasses copper is expected to provide mixed conduction with contributions from copper ions as well as from polarons to ionic and electronic conductivity, respectively. Different compositions belonging to the (50-x)Li 2O-xCu 2O-50P 2O 5 (0<x<20 mol%) system were synthesized by melt quench method. The P 2O 5 mol% was kept constant at 50 mol% while the effect of both Cu 2O and Li 2O on the electrical properties of the glass material was investigated considering the progressive substitution of the mol% Cu 2O by Li 2O. Varying the mole percentage of copper oxide in lithium cuprous phosphate (Li 2O-Cu 2O-P 2O 5) system, we are assessing these relative contributions to overall conduction process
Electrical conductivity of copper lithium phosphate glasses
No full textCopper based oxide glasses are especially interesting for the possibility of ionic-electronic mixed conduction, which has potential applications in energy and switching devices. Accordingly, lithium metaphosphate glasses are investigated within the (100-x) Li2O - xCu2O - 50P2O5 series, where Li+ ions are gradually replaced by copper ions. Based on the changes in glass transition temperature and thermal stability via structural modification, the glasses are shown to be predominantly ionic conductors. In fact, they exhibit signs of classic mixed mobile ion effect (MMIE), a hallmark of ion conduction in glass, which would be due to Li+ and Cu+ ions in the present case. © 2013 Elsevier B.V. All rights reserved
Lithium vanado-phosphate glasses: Structure and dynamics properties studied by molecular dynamics simulations
No full textLithium vanado-phosphate glasses have been designated as possible cathode material for the next generation of solid state batteries, due to their high conductivity and mixed electronic–ionic conducting behaviours, which derive from the small polaron hopping between the vanadium ions with different valence state and the lithium ion diffusion. Therefore, the understanding of the behaviour of these glasses at the atomistic level can be an important aspect in designing compositions for these applications. To reach this goal, the structure and lithium ion diffusion behaviour in lithium vanado-phosphate glasses with mixed V4 + and V5 + ions were studied using molecular dynamics simulations. The results show that vanadium oxide generally plays an intermediate role in glass structure while there are subtle details depending on its concentration and oxidation states. The phosphorus network is depolymerized by the content of vanadium oxide, but phosphorus ions always contribute to the glass network, interposing to vanadium polyhedra. The V4 +single bondOsingle bondV5 + linkages, responsible for the polaron hopping mechanism, show a linear dependence to the V2O5/P2O5 ratio, which highlights a strong role of the interaction between the former ions. The lithium ion diffusion was studied by mean square displacement calculations and it was found that the self-diffusion coefficient just depends on the Li content
Evaluation of the correlations between temperature, humidity, incident UV light and the photocatalytic activity of TiO2films using a rationale approach
No full textThe effect of temperature, humidity and incident UV light on the photocatalytic activity of two TiO2filmswith different microstructures (dense and mesoporous) was explored in terms of stearic acid degradation.Previous works reported in the literature suggest that the activity of TiO2films does not only depend onsingle factors but also on interactions between them. Hence, the design of experiments (DoE) approachwas used in this work to plan the experiments in a systematic way, simultaneously considering severalvariables. This approach provided an efficient working strategy to explore both individual and interactioneffects on the photocatalytic activity of the films. The statistical evidence found here revealed that singlefactors temperature and mesoporous microstructure have the strongest positive effect on the efficiencyof the films. In the case of temperature, this was explained by easier degradation and/or desorption ofreaction intermediates. On the other hand, the positive effect of the mesoporous microstructure wascorrelated with its large surface area. An interaction factor between temperature and incident UV lightalso affects the activity of the films. Results suggest that this phenomenon depends of the degree of filmhydration before the deposition of SA
Structural Insight into Transition Metal Oxide containing glasses by Molecular Dynamic Simulations
No full textIn the last years, glass research focused particular attention on transition metal oxide containing systems for semi-conductive applications, for instance glasses for solid-state devices and secondary batteries. In glass matrices, transition metal ions show multiple oxidation states that lead to peculiar structures and to highly complex systems, which produce interesting optical, electrical and magnetic properties. Computational methods have been largely employed as complementary tool to experimental techniques, in order to improve the knowledge on the materials and their performances. In this work, Molecular Dynamic (MD) simulations have been performed on a series of alkali vanado-phosphate glasses in order to gain deep comprehension of the glass structure. The short and medium range order of the V4+ and the V5+ sites in terms of coordination, pair distribution function, V–O–V linkages, bridging and non-bridging oxygen distributions were calculated and discussed. Finally, the comparison between MD and experimental results shows a very good agreement allowing the validation of the computational models and highlights the correlations between the structure and the conduction mechanism in these glasses. This allows enriching the know-how on these glass systems that result still ambiguous until now
Preparation and Characterization of LAS Glass Based Materials for Dental Applications
No full textGlass ceramic materials are widely used in dental application because of their strong
similarity with natural teeth. In this study LAS glass ceramic/glass materials were prepared by
glazing processing and characterized in terms of mechanical flexural strength. The selected glass
ceramic support derives from an industrial process. Different glasses were applied to the glass
ceramic support in order to investigate firstly their effect on the glass ceramic/glass interface and
secondly how these structural changes are correlated to the flexural strength property. Different
thermal cycles were applied to the glass ceramic in order to promote the increasing of mechanical
flexural strength. Preliminary results clearly points out that the application of a glass on the support
leads to the decrease of the flexural strength if compared to the materials without any coating
applied
LCA of microwaves absorbers obtained from copper slags
No full textCopper slag is generated during pyrometallurgical production of copper from copper ores containing materials like iron, alumina, calcium oxide and silica. Every ton of metal production generates about 1,63 ton of slag [1] which dumping or disposal cause environmental and space problems [2,3,4]. Despite its high iron content, this slag is currently disposed of in landfills, further processed as inert material, or used as an abrasive in industrial processes. However, this last option is not a sustainable solution, because the granules derived from the slag and used as an abrasive are themselves disposed of after re-use. However, because it is composed of iron oxides and silicates, the slag has semi-conductive and mild ferromagnetic properties and could be used to produce innovative advanced materials for heating applications, substituting materials with much higher embodied energy and bringing environmental benefit
Improvement of color quality and reduction of defects in the ink jet-printing technology for ceramic tiles production: A Design of Experiments study
Full text linkThe aim of the present work was to study the effect of different process parameters on the color and defects of tiles produced by ink-jet printing technology. The Design of Experiment approach was used to guarantee a rational planning of the experiments and to ensure objective conclusions through the statistical analysis of the data. Particularly, correlations between the process parameters and the quality of decorated tiles in terms of color and presence of surface defects were extensively investigated. Microstructural analysis was used to explain the results derived by the statistical analysis of the data obtained by the rational plan of the experiments allowing further insight in the structural features and mechanisms correlated to the macroscopic properties of the tiles. The study supplied an efficient way to control the final quality of the decorated tiles satisfying the quality standards required by the market demand. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved
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