Tough silicon carbide macro/mesocellular crack-free monolithic foams
Résumé
Taking the benefit of Si(HIPE) as a hard monolithic template to shape macro-mesoporous foams by using polycarbosilane as pre-ceramic precursor beta-SiC, macro/mesocellular foams have been synthesized. Both macroscopic Plateau border morphology and final mechanical properties can be tuned through varying the starting amount of polycarbosilane precursor. Resulting silicon carbide foams, labeled SiC(HIPE), are composed of beta-SiC at the microscopic length scale, while bearing 110 m(2) g(-1) as specific area at the mesoscopic length scale, and up to 92% of macroporosity. The as-synthesized crack-free SiC(HIPE) monolithic foams are associated with outstanding mechanical properties as, for instance, 50-58 MPa of compression Young modulus. The thermal behaviors of these foams are assessed with bulk heat capacities comprising between 0.15 J g(-1) K(-1) to 0.55 J g(-1) K(-1) that decrease when the foam porosity increases, while their heat conductivities are following the same rules ranging from 2.6 to 4.6 W m(-1) K(-1).