Papers by Author: R. Pailler

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Authors: Sebastien Bertrand, O. Boisron, R. Pailler, Jacques Lamon, Roger R. Naslain
Authors: F. Lamouroux, Sebastien Bertrand, R. Pailler, Roger R. Naslain
Authors: Roger R. Naslain, R. Pailler, G. Chollon, R. Bodet, H. Hannache
Authors: J.C. Ichard, R. Pailler, Jacques Lamon
Abstract: The purpose of the study was to increase the thermal conductivity of multilayered and self-sealing ceramic matrix composites via the silicon melt infiltration process. The first step of the process consisted in filling porosity using various organic xerogels by the sol-gel route. Carbon xerogels obtained by subsequent pyrolysis may reduce and homogenize the porous network within the composite. Cracking of the xerogels due to volumic shrinkage occurring during air drying may be decreased by controlling the initial parameters as concerns the gel solution and/or by operating a second impregnation/pyrolysis step. Filling of such composites by liquid silicon revealed that a specific route and particular conditions are necessary to eliminate porosity by controlling gas production species from pore surface at high temperature. This may be achieved through a directional flow and using highly viscous silicon (thanks to a localized wick), and by keeping the sides of the materials permeable to gas. This led to composite materials with a thermal conductivity which was four times as high as that of those materials densified via CVI. An increase in mechanical properties was also observed.
Authors: S. Labruquere, R. Pailler, Roger R. Naslain, B. Desbat
Authors: N. Eberling-Fux, R. Pailler, A. Guette, Sebastien Bertrand, Eric Philippe
Abstract: 3D woven carbon fibre preforms (~ 2 mm thickness) were impregnated with single or mixture of non oxide ceramic nanoscale powders in ethanolic suspensions using electrophoretic deposition (EPD). The measurement of the ζ potential of the suspension compared with its behaviour in sedimentation permits to conclude about the optimal concentration of surfactant necessary to get the most stable suspension. The experimental results were in agreement with the theoretical ones obtained using DLVO (Derjaguin, Landau, Verwey and Overbeek) theory. EPDs were carried out by applying a constant voltage between the 3D carbon fibre preform serving as deposition electrode and counter electrodes in graphite. The effect of the powder concentration on the rate and the quality of impregnation was studied. A qualitative model based on the experimental results and literature was then proposed. Experiments were not only carried out on raw 3D fibrous preforms but also on preforms with interphases. SEM and optical micrographies of fractured and polished sections of the infiltrated fabrics revealed that a quite high degree of infiltration (rates of impregnation estimated between 50 and 70 %) was obtained. At last, the composite was densified using spark plasma sintering (SPS).
Authors: S. Fouquet, Stéphane Jouannigot, Joël Alexis, R. Pailler, Xavier Bourrat, A. Guette, Roger R. Naslain
Authors: Roger R. Naslain, R. Pailler, Xavier Bourrat, Sebastien Bertrand, F. Lamouroux
Authors: Roger R. Naslain, R. Pailler, Xavier Bourrat, Gerard Vignoles
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