Search results for "Note"
showing 10 items of 10709 documents
Valorisation of industrial iron oxide waste to produce magnetic barium hexaferrite
2016
Barium M-type hexagonal ferrite (BaM, BaFe12O19) is an immensely important magnetic material, which we have successfully made from the simple valorisation of Fe-rich industrial waste from steel wire drawing, with addition of BaCO3 and heating in air to 1000 degrees C. The optimum ratio of Fe. Ba (producing 86 wt% BaM) was found to be 11: 1 (non-stoichiometric), and secondary phases of alpha-Fe2O3 (non-magnetic) and ZnFe2O4 (poorly antiferromagnetic) were always present. This material consisted of small submicron platelets. A hard magnetic ferrite was produced with Ms=48.6 A m(2) kg(-1) and H-c=211.5 kA m(-1). The highest density was achieved by sintering samples with Fe: Ba ratios of 11: 1 …
Nanoscale Chemical Interaction Enhances the Physical Properties of Bioglass Composites
2013
Bioglasses are favorable biomaterials for bone tissue engineering; however, their applications are limited due to their brittleness. In addition, the early failure in the interface is a common problem of composites of bioglass and a polymer with high mechanical strength. This effect is due to the phase separation, nonhomogeneous mixture, nonuniform mechanical strength, and different degradation properties of two compounds. To address these issues, in this study a nanoscale interaction between poly(methyl methacrylate) (PMMA) and bioactive glass was formed via silane coupling agent (3-trimethoxysilyl)propyl methacrylate (MPMA). A monolith was produced at optimum composition from this hybrid …
Fracture resistance and the mode of failure produced in metal-free crowns cemented onto zirconia abutments in dental implants.
2019
The purpose of the investigation was to analyze fracture resistance and mode of failure of zirconium oxide (zirconia) abutments placed on dental implants bearing crowns of different esthetic materials: zirconia, lithium disilicate (LDS), and nano-ceramic resin, for replacing single teeth in the anterior sector. Eighty implant-abutment-crown units were divided into four groups: Group T-MC (control): 20 metal-ceramic crowns cemented onto titanium abutments; Group Z-Z: 20 zirconia crowns on zirconia abutments; Group Z-LD: 20 lithium disilicate crowns on zirconia abutments; and Group Z-NCR: 20 nano-ceramic resin crowns on zirconia abutments. Specimens underwent a fatiguing process (dynamic load…
A comparison between photocatalytic and catalytic oxidation of 2-Propanol over Au/TiO2-CeO2 catalysts
2016
Abstract Photocatalytic and catalytic oxidation of 2-propanol, representative of volatile organic compounds (VOC’s), were compared over mixed TiO 2 –CeO 2 -based catalysts. The effect of different amounts of CeO 2 and the presence of gold (1 wt%) on TiO 2 was investigated. In the photocatalytic oxidation CeO 2 had a negative effect on the performance towards the alcohol conversion of both TiO 2 –CeO 2 and Au/TiO 2 –CeO 2 catalysts, being Au/TiO 2 the most active system. On the contrary mixed TiO 2 –CeO 2 and Au/TiO 2 –CeO 2 samples showed a higher catalytic oxidation efficiency for 2-propanol conversion compared to the single oxides. In this case Au/CeO 2 catalyst had the best performance. …
Exploring the photothermo-catalytic performance of brookite tio2-ceo2 composites
2020
The thermocatalytic, photocatalytic and photothermo-catalytic oxidation of some volatile organic compounds (VOCs), 2-propanol, ethanol and toluene, was investigated over brookite TiO2-CeO2 composites. The multi-catalytic approach based on the synergistic effect between solar photocatalysis and thermocatalysis led to the considerable decrease in the conversion temperatures of the organic compounds. In particular, in the photothermo-catalytic runs, for the most active samples (TiO2-3 wt% CeO2 and TiO2-5 wt% CeO2), the temperature at which 90% of VOC conversion occurred was about 60 °
Mechanical performance of experimental acrylic resins modified by nanoparticles after chemical and mechanical degradation.
2020
Background Different materials have been incorporated into the polymethylmethacrylate matrix to improve its performance. The aim of this study was to evaluate the degree of conversion (DC), the flexural strength (FS), the elasticity modulus (EM), and the effect of exposure to food-simulating liquids prior to brushing simulation on the gloss loss (GL) of experimental acrylic resins modified by nanoparticles. Material and methods Three different types of nanoparticles; silicon oxide (SiO2), cerium oxide (CeO2) and titanium oxide (TiO2) were added to a poly (methylmethacrylate) matrix, in proportions of 0.5wt%, 1wt% and 3wt% each, forming nine experimental groups. The acrylic resin was also te…
High efficiency of Pt2+ - CeO2 novel thin film catalyst as anode for proton exchange membrane fuel cells
2016
Abstract The elevated price of Pt limits the large-scale implementation of commercial proton exchange membrane fuel cells, which effectively convert chemical energy into electricity. In order to increase the cost-efficiency in proton-exchange membrane fuel cells, we have designed a family of novel anode catalysts consisting of thin films of ceria with low Pt loadings sputtered on a nanostructured carbon support. Remarkably, only such small amounts of Pt are necessary for achieving power density values comparable to the reference commercial catalysts, which results in excellent specific activities of our samples. By combining photoelectron spectroscopy and catalytic performance analysis, we …
Growth of nano-porous Pt-doped cerium oxide thin films on glassy carbon substrate
2013
Abstract Glassy carbon (GC) substrates were treated by the oxygen plasma over several periods of time. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) study showed the dramatic influence of oxygen plasma on the morphology of glassy carbon. The treatment leads to the formation of nanostructured surface, which consists of well separated rod-like nanostructures oriented perpendicularly to the substrate surface. The surface roughness was found to increase with increasing treatment time. By using magnetron co-sputtering of platinum and cerium oxide we can prepare oxide layers continuously doped with Pt atoms during the growth. This tec…
Preparation of magnetron sputtered thin cerium oxide films with a large surface on silicon substrates using carbonaceous interlayers.
2013
The study focuses on preparation of thin cerium oxide films with a porous structure prepared by rf magnetron sputtering on a silicon wafer substrate using amorphous carbon (a-C) and nitrogenated amorphous carbon films (CNx) as an interlayer. We show that the structure and morphology of the deposited layers depend on the oxygen concentration in working gas used for cerium oxide deposition. Considerable erosion of the carbonaceous interlayer accompanied by the formation of highly porous carbon/cerium oxide bilayer systems is reported. Etching of the carbon interlayer with oxygen species occurring simultaneously with cerium oxide film growth is considered to be the driving force for this effec…
Screening of ceria-based catalysts for internal methane reforming in low temperature SOFC
2010
Gaudillere, Cyril Vernoux, Philippe Mirodatos, Claude Caboche, Gilles Farrusseng, David 6th World Congress on Oxidation Catalysis (6WCOC) JUL 05-10, 2009 Lille, FRANCE; International audience; Ceria-based catalysts have been assessed for internal methane reforming at low temperature (400-600 C) in Solid Oxide Fuel Cell (SOFC) A combinatorial library of 15 metal (Cu Pt Ni) supported ceria was prepared using wet impregnation method The ceria-based oxides are undoped or doped with metal transition (Zr) or by rare earth (Gd or Pr) The effect of the metal the dopant and the surface area on the catalytic performances was investigated in high-throughput manner using a 16-parallel reactor The catal…