Search results for "Metals"
showing 10 items of 2013 documents
Thermo-oxidative resistant nanocomposites containing novel hybrid-nanoparticles based on natural polyphenol and carbon nanotubes
2015
Abstract Quercetin (Q), a natural antioxidant molecule, is physically immobilized onto multi-walled carbon nanotubes (CNTs) bearing covalently-linked long-chain alkyl functional groups, and the so obtained hybrid-nanoparticles are used to prepare Ultra High Molecular Weight PolyEthylene-based nanocomposite films with enhanced thermo-oxidation resistance. The effective immobilization of the Q molecules is confirmed by spectroscopic (micro-Raman, ATR-FTIR, and FTIR) and thermo-gravimetric analyses, and the influence of the nanoparticles on the rheological behaviour and thermo-oxidative stability of the nanocomposites are investigated. Rheological analyses (linear viscoelasticity and stress re…
Effect of interfacial area on heterogeneous free radical grafting of vinyl monomers in supercritical carbon dioxide: Grafting of acrylic acid on poly…
2014
The role of the polymer interfacial area on free radical grafting of acrylic acid (AA) onto poly(vinylidenefluoride) (PVDF) was studied at 65°C using supercritical carbon dioxide (scCO2) as a solvent and swelling agent, benzoylperoxide (BPO) as chemical initiator and PVDF nanoparticles as polymer matrix. Under adopted conditions PVDF particles do not melt neither dissolve in the reaction medium and FTIR analyses performed on carefully washed nanoparticles confirmed the achievement of high grafting levels. The mass fraction of grafted AA increased with the grafting time and the BPO concentration while it decreased when the density of the fluid phase was enhanced. Collected results suggest th…
Sintering of Fe2NiO4 with an internal binder: a way to obtain a very dense material
2003
Abstract The coupled synthesis and sintering of Fe2NiO4 can be carried out from the calcination under air at high temperatures (>1200 °C) of precompacted (under 12 MPa) pellets of different mixtures: NiO/α-Fe2O3; NiO/α-Fe2O3/Fe; NiO/α-Fe2O3/Ni. The densest material is obtained at 1200 °C only from the following mixture: NiO (40 mol%), α-Fe2O3 (50 mol%) and Ni (10 mol%). Because the metallic nickel is very ductile, it is used as an internal binder in order to enhance the precompacting of the samples. Moreover, the role of nickel is to enhance the sintering reaction. This route leads to a final material of relative density close to 98±2%.
A new method of nanocrystalline nickel powder formation by magnetron sputtering on the water-soluble substrates
2018
Due to the accurate and relatively easy control magnetron sputtering is an attractive technique for the synthesis of metallic particles. This work describes a new method of nickel powder production by depositing nickel on the surface of sodium chloride particles which were used as the template and are soluble in water. Ni powder with flake-like structure was obtained after washing Ni coated salt particles in ultrasonic cleaner. Salt particles and nickel powder were characterized using scanning electron microscope (SEM), energy-dispersive x-ray spectrometer, XRD and X-ray photoelectron spectroscopy (XPS) techniques. SEM images showed that thickness of the received Ni particles varied in the …
Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges
2011
A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then invest…
Dislocation interaction with C in α-Fe: a comparison between atomic simulations and elasticity theory
2008
International audience; The interaction of C atoms with a screw and an edge dislocation is modelled at an atomic scale using an empirical Fe-C interatomic potential based on the Embedded Atom Method (EAM) and molecular statics simulations. Results of atomic simulations are compared with predictions of elasticity theory. It is shown that a quantitative agreement can be obtained between both modelling techniques as long as anisotropic elastic calculations are performed and both the dilatation and the tetragonal distortion induced by the C interstitial are considered. Using isotropic elasticity allows to predict the main trends of the interaction and considering only the interstitial dilatatio…
Thermal disorder and correlation effects in anti-perovskite-type copper nitride
2017
This work has been supported by the Latvian National Research Program IMIS2. The EXAFS experiment has been financed from the European Community's Seventh Framework Programme under grant agreement No. 226716 (Project I-20100098 EC). J.T. also gratefully acknowledges support from the National Science Foundation under the DMREF program Grant No. CHE-1534184.
Thermal and dynamic mechanical properties of beeswax-halloysite nanocomposites for consolidating waterlogged archaeological woods
2015
Abstract Thermal and mechanical properties were determined for the halloysite nanotubes (HNT)/beeswax composites at various compositions. The beeswax degradation temperatures and time course, provided by thermogravimetry (TG), evidenced the improvement of the thermal properties operated by HNT. Differential scanning calorimetry (DSC) allowed us to determine the enthalpy of melting as well as the time course of the melting process for beeswax. A slight loss of beeswax crystallinity was observed upon HNT addition. The dynamical mechanical analysis (DMA) provided the loss and the storage modulus for the nanocomposites upon heating and it was shown that the nanoclays create an inorganic framewo…
Polymeric scaffolds prepared via thermally induced phase separation: Tuning of structure and morphology
2008
Scaffolds suitable for tissue engineering applications like dermal reconstruction were prepared by Thermally Induced Phase Separation (TIPS) starting from a ternary solution PLLA/dioxane/water. The experimental protocol consisted of three consecutive steps, a first quench from the homogeneous solution to an appropriate demixing temperature (within the metastable region), a holding stage for a given residence time, and a final quench from the demixing temperature to a low temperature (within the unstable region). A large variety of morphologies, in terms of average pore size and interconnection, were obtained upon modifying the demixing time and temperature, owing to the interplay of nucleat…
Graphene as a carbon source effects the nanometallurgy of nickel in Ni,Mn layered double hydroxide-graphene oxide composites.
2012
[EN] Thermal treatment of the hybrid material formed by the spontaneous precipitation of graphene oxide and Ni,Mn layered double hydroxide leads to the segregation of nickel metal nanoparticles (Ni NPs) and the decomposition of graphene to CO2. Increasing the temperature increases the Ni NP size and results in the complete disappearance of graphene.