Integrative Chemistry toward Biosourced SiC Macrocellular Foams Bearing Unprecented Heat Transport Properties
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Integrative Chemistry toward Biosourced SiC Macrocellular Foams Bearing Unprecented Heat Transport Properties
Simona Ungureanu1,2, Marc Birot2, Gérard Vignoles3, Christophe Lorette4, Gilles Sigaud1, Hervé Deleuze2, Rénal Backov1 1
Centre de Recherche Paul Pascal, UPR 8641-CNRS, Université de Bordeaux, 115 Avenue Albert Schweitzer, 33600 Pessac, France Université de Bordeaux, Institut des Sciences Moléculaires (ISM) UMR 5255 CNRS, 351 Cours de la Libération, 33405 Talence, France 3 Université de Bordeaux, Laboratoire des Composites Thermostructuraux, UMR 5801 CNRSUB1-CEA-Snecma Propulsion Solide, 3 Allée de la Boétie, 33600 Pessac, France 4 CEA, Laboratoire des Composites Thermostructuraux, UMR 5801 CNRS-UB1-CEA-Snecma Propulsion Solide, 3 Allée de la Boétie, 33600 Pessac, France 2
ABSTRACT Black liquor is a by-product of the paper mill Kraft process that deserves more valorization than its present use as low-grade fuel. In this work, SiC/C composite foams were prepared for the first time from concentrated emulsions by carbothermal reduction of bio-sourced precursors combining sodium silicate by lignin at 1400°C. The composition of the materials was determined by XRD, FTIR and Raman analyses. Their porous structure was characterized by SEM, mercury intrusion porosimetry, and nitrogen sorption, while their thermal properties were measured by TGA and dynamic DSC. Concerning their heat transport properties, we found out that when the starting lignin content was increased, the final C/Si ratio, the specific surface area and the heat diffusivity increased as well. Its high values were attributed to a cooperative effect between radiative heat transfer and the presence of partially graphitized carbon. INTRODUCTION Trends toward transformation of waste/biomass to valuable materials are growing stronger because of the depletion of natural resources and increasing of greenhouse emission [1]. Moreover, chemistry of materials relies strongly on rational design over all length scales, where final enhanced functionality will ensure the overall synthetic pathway to be applied. From this way of thinking has recently emerged the concept of Integrative Chemistry [2]. One synthetic path combines sol-gel chemistry with lyotropic mesophases and concentrated direct emulsions to promote either inorganic Si(HIPE) [3] or hybrid organic-inorganic foams named OrganoSi(HIPE) [4] (the acronym HIPE relies for High Internal Phase Emulsion) [5]. Recently, we used Si(HIPE) macrocellular foams as hard template to produce the parent carbonaceous macrocellular foams [6] bearing standard application in Li-ion battery electrodes and chemical
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electro-capacitors devices, hydrogen storage when modified with Li(BH4) [7]. This process has been also extended to the morphosyntheses of boronitrite BN(HIPE) [8] and silicon carbide/carbon composite SiC/C(HIPE) [9]. Indeed, silicon carbide (SiC) is an important nonoxide ceramic associated to a set of unique properties such as high thermal stability, high heat conductance addressed through small heat expan
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