Search results for "matériaux"
showing 10 items of 117 documents
Weld pool surface temperature measurement from polarization state of thermal emission
2014
This paper presents a passive polarimetry method using a division of aperture optical device in order to measure the temperature distribution at the weld pool surface. Thermal emission from a hot liquid metal was investigated at a near-infrared wavelength corresponding to a blind spectral window of a helium plasma generated during gas tungsten arc welding process. The refractive index of liquid metal and the surface radiance are deduced from the polarisation state of thermal emissions. Based upon the knowledge of both characteristics, the temperature distribution can be calculated. Conseil Régional de Bourgogne
Caspartin and calprismin, two proteins of the shell calcitic prisms of the Mediterranean fan mussel Pinna nobilis.
2005
We used the combination of preparative electrophoresis and immunological detection to isolate two new proteins from the shell calcitic prisms of Pinna nobilis, the Mediterranean fan mussel. The amino acid composition of these proteins was determined. Both proteins are soluble, intracrystalline, and acidic. The 38-kDa protein is glycosylated; the 17-kDa one is not. Ala, Asx, Thr, and Pro represent the dominant residues of the 38-kDa protein, named calprismin. An N-terminal sequence was obtained from calprismin. This sequence, which comprises a pattern of 4 cysteine residues, is not related to any known protein. The second protein, named caspartin, exhibits an unusual amino acid composition, …
Implementation and optimization of the properties of a sandwich structure in biobased materials (fibres and Hemp wood) with an expanded polystyrene m…
2017
Due to the rapidly improving functionality of building materials, and increasingly complicated human resource management issues, the traditional cement-based building materials of the past are becoming less and less desirable.These outdated materials are being replaced by new structures of wall that better optimize choices of materials and their layouts. In this study, we propose a multi-function structure to be the unit of a typical wall (individual house), which can be produced via the use of inexpensive materials and classic manufacturing processes. To achieve this, we chose the renewable agricultural source of the hemp plant (hemp yarns and hemp shive particles), along with recycled exp…
Impact behaviour of flax/epoxy composite plates
2015
This paper presents an experimental investigation of the impact behaviour of flax/epoxy composite plates submitted to low-velocity transverse impact. Low energy drop-weight impact tests have been performed on two types of quasi-isotropic flax/epoxy composites, rectangularly shaped with edges lengths of 142 mm × 94 mm and 2.85 mm thick. Residual properties have been assessed by compression after impact tests. A detailed description of damage development, especially the increase of the rear face crack with respect to the impact energy is given by the microscopic observation. The influence of impact damage on the residual strength is described. A loss of 15%–30% in compression resistance was n…
NaCl induced corrosion of Ti-6Al-4V alloy at high temperature
2016
International audience; This paper presents a study on the Ti-6Al-4V behaviour in presence of NaCl deposit under dry and moistair environments at 560◦C. The results evidence a detrimental effect of the NaCl deposit with a synergisticeffect in presence of moist air environment. Treatments under dry and moist air with NaCl deposit for600 h, lead respectively to weight gains per unit area 5 and 15 times higher than observed under classicoxidation in dry air. Enhancement of the corrosion phenomenon is attributed to the presence of gaseousmetal chlorides, leading to the establishment of an active corrosion process.
A comparative study of fatigue behaviour of flax/epoxy and glass/epoxy composites
2012
Experimental investigations on flax and glass fabrics reinforced epoxy specimens, i.e. FFRE and GFRE, submitted to fatigue tests are presented in this paper. Samples having [0/90]3S and [±45]3S stacking sequences, with similar fibre volume fractions have been tested under tension–tension fatigue loading. The specific stress-number of cycles to failure (S–N) curves, show that for the [0/90]3S specimens, FFRE have lower fatigue endurance than GFRE, but the [±45]3S FFRE specimens offer better specific fatigue endurance than similar GFRE, in the studied life range (<2 × 10^6). Overall, the three-stage stiffness degradation is observed in all cases except for [0/90]3S FFRE specimens, which prese…
Influence of the microstructure and laser shock processing (LSP) on the corrosion behaviour of the AA2050-T8 aluminium alloy
2011
International audience; The corrosion behaviour of AA2050-T8 was studied after polishing and after laser shock processing (LSP) treatment using the electrochemical microcell technique and the SVET. After polishing, pitting at constituent particles and intergranular corrosion were observed. By contrast, no intergranular corrosion developed after LSP. Microcell measurements revealed that LSP increases the pitting potential. SVET measurements revealed that local anodic currents are systematically lower on LSP-treated surfaces than on polished ones. The current density on the LSP-treated surface remains constant around 50 μA cm−2 up to 123 min after immersion, while on the polished surface it r…
Cooperativity Scaling and Free Volume in Plasticized Polylactide
2019
The authors would like to thank the region Haute Normandie for their financial support and the acquisition of the Broadband Dielectric Spectrometer. R.G. acknowledges U.S. National Science Foundation (Grant no. DMR-1725188) for the acquisition of PAL spectrometer. The experimental evidence of the increase of activation energy associated with the super Arrhenius behavior governing amorphous polylactide by free volume variations has been obtained through a combination of calorimetric, dielectric, and positron annihilation lifetime measurements. The amount of free volume in polylactide was controlled by the amount of acetyltributylcitrate plasticizer in the composition. Plasticization is shown…
Local electrochemical impedance spectroscopy study of the influence of ageing in air and laser shock processing on the micro-electrochemical behaviou…
2011
International audience; In the present paper, the micro-electrochemical behaviour of AA2050-T8 in 0.1 M NaCl was first studied after polishing by means of local electrochemical impedance spectroscopy and field-emission scanning electron microscopy/electron dispersive spectroscopy (FE-SEM/EDS). The influence of ageing in air and LSP was then investigated. Ageing in air for three months led to an increase in the charge transfer resistance. This was clearly observed in sites surrounding constituent particles where the charge transfer resistance was in the order of 1 MΩ cm2 (instead of 10-3 MΩ cm2 after polishing). Increased passivity around particles was confirmed from FE-SEM/EDS analysis. On …
Generation and characterization of T40/A5754 interfaces with lasers
2014
Laser-induced reactive wetting and brazing of T40 titanium with A5754 aluminum alloy with 1.5 mm thickness was carried out in lap-joint configuration, with or without the use of Al5Si filler wire. A 2.4 mm diameter laser spot was positioned on the aluminum side to provoke spreading and wetting of the lower titanium sheet, with relatively low scanning speeds (0.1 to 0.6 m/min). Process conditions did not play a very significant role on mechanical strengths, which were shown to reach 250-300 N/mm on a large range of laser power and scanning speeds. In all cases considered, the fracture during tensile testing occurred next to the TiAl3 interface, but in the aluminum fusion zone. In a second st…