Tourlonias M.,CNRS Textile Mechanics and Physics Laboratory |
Bueno M.-A.,CNRS Textile Mechanics and Physics Laboratory |
Poquillon D.,Inter - University Research and Engineering Center on Materials
Composites Part A: Applied Science and Manufacturing | Year: 2017
The aim of this study conducted on carbon tows and single fibres is to highlight some friction behaviours to help better understand the friction mechanisms that occur during the manufacture of carbon composites. These mechanisms are responsible for damage that reduces the specifications and lifetime of mechanical parts. An experiment has been developed in order to rub together two carbon tows, or two single carbon fibres (with a diameter down to 5 µm), at an angle of 90°. The influences of friction velocity, normal load, and type of carbon fibre have been studied. For both tows and fibres the friction follows the Coulomb's law because there is no influence of the velocity and the normal load in the tested range. The rearrangement of fibres within the tow has been shown to be fundamental. For the single fibre, the role of the Young's modulus and the sizing treatment is important. © 2017 Elsevier Ltd
Sanz V.,University of Surrey |
Borowiak E.,West Pomeranian University of Technology |
Lukanov P.,Inter - University Research and Engineering Center on Materials |
Galibert A.M.,Inter - University Research and Engineering Center on Materials |
And 4 more authors.
Carbon | Year: 2011
The use of carbon nanotubes as a gene delivery system has been extensively studied in recent years owing to its potential advantages over viral vectors. To achieve this goal, carbon nanotubes have to be functionalized to become compatible with aqueous media and to bind the genetic material. To establish the best conditions for plasmid DNA binding, we compare the dispersion properties of single-, double- and multi-walled carbon nanotubes (SWCNTs, DWCNTs and MWCNTs, respectively) functionalized with a variety of surfactants by non-covalent attachment. The DNA binding properties of the functionalized carbon nanotubes were studied and compared by electrophoresis. Furthermore, a bilayer functionalization method for DNA binding on SWCNTs was developed that utilized RNA-wrapping to solubilize the nanotubes and cationic polymers as a bridge between nanotubes and DNA. © 2010 Elsevier Ltd. All rights reserved.
Kwon J.,University of Texas at Dallas |
Ducere J.M.,Hoffmann-La Roche |
Ducere J.M.,Toulouse 1 University Capitole |
Alphonse P.,Inter - University Research and Engineering Center on Materials |
And 11 more authors.
ACS Applied Materials and Interfaces | Year: 2013
Interface layers between reactive and energetic materials in nanolaminates or nanoenergetic materials are believed to play a crucial role in the properties of nanoenergetic systems. Typically, in the case of Metastable Interstitial Composite nanolaminates, the interface layer between the metal and oxide controls the onset reaction temperature, reaction kinetics, and stability at low temperature. So far, the formation of these interfacial layers is not well understood for lack of in situ characterization, leading to a poor control of important properties. We have combined in situ infrared spectroscopy and ex situ X-ray photoelectron spectroscopy, differential scanning calorimetry, and high resolution transmission electron microscopy, in conjunction with first-principles calculations to identify the stable configurations that can occur at the interface and determine the kinetic barriers for their formation. We find that (i) an interface layer formed during physical deposition of aluminum is composed of a mixture of Cu, O, and Al through Al penetration into CuO and constitutes a poor diffusion barrier (i.e., with spurious exothermic reactions at lower temperature), and in contrast, (ii) atomic layer deposition (ALD) of alumina layers using trimethylaluminum (TMA) produces a conformal coating that effectively prevents Al diffusion even for ultrathin layer thicknesses (∼0.5 nm), resulting in better stability at low temperature and reduced reactivity. Importantly, the initial reaction of TMA with CuO leads to the extraction of oxygen from CuO to form an amorphous interfacial layer that is an important component for superior protection properties of the interface and is responsible for the high system stability. Thus, while Al e-beam evaporation and ALD growth of an alumina layer on CuO both lead to CuO reduction, the mechanism for oxygen removal is different, directly affecting the resistance to Al diffusion. This work reveals that it is the nature of the monolayer interface between CuO and alumina/Al rather than the thickness of the alumina layer that controls the kinetics of Al diffusion, underscoring the importance of the chemical bonding at the interface in these energetic materials. © 2013 American Chemical Society.
Lacaze J.,Inter - University Research and Engineering Center on Materials |
Sertucha J.,IK |
Magnusson Aberg L.,Elkem ASA
ISIJ International | Year: 2016
A review of past works on the formation of ferrite and pearlite in nodular cast iron is proposed. The effects of cooling rate after solidification and of nodule count on the formation of both constituents are stressed, though much emphasis is put on alloying elements and impurities. © 2016 ISIJ.
Severac F.,Hoffmann-La Roche |
Severac F.,National Polytechnic Institute of Toulouse |
Alphonse P.,Inter - University Research and Engineering Center on Materials |
Esteve A.,Hoffmann-La Roche |
And 5 more authors.
Advanced Functional Materials | Year: 2012
Over the next few years, it is expected that new, energetic, multifunctional materials will be engineered. There is a need for new methods to assemble such materials from manufactured nanopowders. In this article, we demonstrate a DNA-directed assembly procedure to produce highly energetic nanocomposites by assembling Al and CuO nanoparticles into micrometer-sized particles of an Al/CuO nanocomposite, which has exquisite energetic performance in comparison with its physically mixed Al/CuO counterparts. Using 80 nm Al nanoparticles, the heat of reaction and the onset temperature are 1.8 kJ g -1 and 410 °C, respectively. This experimental achievement relies on the development of simple and reliable protocols to disperse and sort metallic and metal oxide nanopowders in aqueous solution and the establishment of specific DNA surface-modification processes for Al and CuO nanoparticles. Overall, our work, which shows that DNA can be used as a structural material to assemble Al/Al, CuO/CuO and Al/CuO composite materials, opens a route for molecular engineering of the material on the nanoscale. The fabrication of high-energy Al/CuO nanocomposites by nanoparticle DNA-directed assembly is demonstrated. The complementarity of the strands attached to the Al and CuO nanoparticles enables the assembly of micrometer-sized aggregates, which release heat upon thermal actuation, to be directed. The actuation temperature of 410°C of these materials is among the lowest published in the literature. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Berne C.,Inter - University Research and Engineering Center on Materials |
Berne C.,ENSIACET |
Andrieu E.,ENSIACET |
Reby J.,CETIM |
And 2 more authors.
Journal of the Electrochemical Society | Year: 2015
The electrochemical behavior of an α,β'-brass CuZn40Pb2 (CW617N) was studied in basic nitrate solutions with various basic pHs and nitrate ion concentrations. In all the chosen experimental conditions, corrosion at the open circuit potential proceeded by the galvanic coupling of the α and β' phases, leading to a surface dezincification of the β' phase. The study showed that the extent of the dezincification was affected by the presence of lead in the alloy but the pH was the major parameter. During polarization tests, a pseudo-passive or a passive stage followed by a breakdown was observed: corrosion phenomena mainly involved copper and zinc dissolution from the β' phase. At pH 11, a Cu2O/PbO layer was efficient in achieving passivity of the brass. At pH 12, a Cu(OH)2-rich surface layer was formed: it was not protective enough, and complete dissolution of the β' phase was observed leading to the removal of lead particles. © 2015 The Electrochemical Society.
Rey C.,CNRS Inter-university Material Research and Engineering |
Combes C.,CNRS Inter-university Material Research and Engineering |
Drouet C.,CNRS Inter-university Material Research and Engineering |
Cazalbou S.,Inter - University Research and Engineering Center on Materials |
And 3 more authors.
Progress in Crystal Growth and Characterization of Materials | Year: 2014
The term biomimetic is used with different meanings; applied to materials it is often intended to denote preparative techniques and/or properties mimicking those of biological materials. Biological nanocrystals are characterized by the existence of non-apatitic domains, which have sometimes been interpreted as a sign of formation of precursor phases. Finally, spectroscopic (FTIR and SS-NMR) analyses of wet samples revealed that the surface hydrated layers were structured, and that the structuralization was related to surface composition and easily altered by fast, reversible ionic exchange, leaving the apatite domains unchanged. The hydrated layer shall not be considered as a Stern double layer but a result of the precipitation process of biomimetic apatites. This layer is believed to decrease the water-crystal interfacial energy and to favor the formation of the nanocrystals in aqueous media. From a thermodynamic point of view, however, the apatite domains are the most stable and with time they develop at the expense of the hydrated layer, incorporating some of the mineral ions presenting this layer.
Suarez R.,Ingenieria |
Sertucha J.,Ingenieria |
Larranaga P.,Ingenieria |
Lacaze J.,Inter - University Research and Engineering Center on Materials
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2016
Appropriate nodularity in ductile iron castings is strongly associated with the presence of high enough not combined Mg dissolved in the melt to cast. However, the residual Mg which is commonly measured for production control accounts for both dissolved Mg and Mg combined as oxides and sulfides. To account for the uncertainties associated with such a control, it is quite usual to over treat the melt with the risk of porosity appearance. A new methodology based on thermal analysis has been developed in the present work so as to estimate the amount of free Mg dissolved in the melt ready for pouring. A combination of Te mixture and a new “reactive mixture” composed of sulfur plus a commercial inoculant has been prepared for this purpose. This reactive mixture is able to transform the magnesium remaining dissolved in the melt to combined forms of this element. Experiments performed both during start of production (when Mg overtreatment is usual) and during normal mass production indicate that important variations of free Mg occur without relevant changes in residual Mg content as determined by spectrometry. The method developed in the present work has shown to be highly effective to detect those melt batches where active Mg content is not high enough for guaranteeing a correct nodularity of castings. Selection of proper active Mg thresholds and a correct inoculation process are critical to avoid “false”-negative results when using this new method. © 2016 The Minerals, Metals & Materials Society and ASM International
Laboulfie F.,Inter - University Research and Engineering Center on Materials |
Hemati M.,Inter - University Research and Engineering Center on Materials |
Lamure A.,Inter - University Research and Engineering Center on Materials |
Diguet S.,Nutritional Products Ltd.
Powder Technology | Year: 2013
Thin layer deposit of a composite material on solid particle surfaces used in the food industry aims to ensure the protection of food powder against aggressive environments such as a moist atmosphere. The layer, having a thickness of a few fractions of millimetre, must have certain physico-chemical properties: it must be compatible with the product, it must be impermeable to water and oxygen, it must have good mechanical strength and good adhesion to the surface of the coated powder. Furthermore the layer must fulfil the regulatory requirements for food ingredients. Film properties like continuity, permeability, and mechanical resistance depend on the choice of the excipients included in the formulation and the operating conditions which can modify the constraints generated at the interface film-powder. As a consequence, the scientific issue consists of combining the local phenomena happening at a microscopic level on the surface of the particle with the processing technology and the process parameters. In a first step, the attention is focussed on the film and its formulation. For this step, films are prepared separately and they are dried under very smooth conditions. Test samples are taken from the formed composite films and contain hydroxypropyl methylcellulose as matrix (67% of dried material), micronised stearic acid as hydrophobic filler (20% of dried material) and a plasticizer (13% of dried material). The film formation procedure and the test method are described in detail. The effect of the type of plasticizer (different grades of PEG) on mechanical, thermal and permeability properties of the coating film is studied. The results show that PEG with higher molecular rate provides a better plasticizing effect for the film but increases the water vapour permeability of the film. © 2012 Elsevier B.V.
Baillieux J.,Inter - University Research and Engineering Center on Materials |
Poquillon D.,Inter - University Research and Engineering Center on Materials |
Malard B.,Inter - University Research and Engineering Center on Materials
Journal of Applied Crystallography | Year: 2016
In this study, the influence of oxygen diffusion on the physical properties of Ti-6Al-2Sn-4Zr-2Mo-0.1Si was examined. Measurements were carried out directly on sample cross sections which were preoxidized at high temperature. The lattice parameter evolution was measured using synchrotron X-ray diffraction and was coupled with microhardness and electron probe microanalyzer results with the aim of highlighting their relationships. The results show that the hardness and oxygen gradients along the oxygen diffusion zone in the alloy are similar to the evolution of the α-phase unit-cell volume quantified by X-ray diffraction. Linear relationships were found between these three parameters. © International Union of Crystallography 2016.