Application of the laser pyrolysis to the synthesis of SiC, TiC and ZrC pre-ceramics nanopowders

International audienceRefractory carbide nanostructured ceramics appear to be promising materials for high temperature applications requiring hard materials such as nuclear energy industry. Such carbide materials are usually obtained with micrometric sizes from the high temperature carboreduction of an oxide phase in a raw mixture of C black and titania or zirconia. TiC and ZrC nanopowders were produced from an intimate mixture of oxide nanograins with free C synthesized by laser pyrolysis from the decomposition of a liquid precursor. The temperature and the duration of the thermal treatment leading to the carburization were decreased, allowing the preservation of the nanoscaled size of the starting grains. A solution of titanium isopropoxide was laser-pyrolysed with ethylene as sensitizer in order to synthesize Ti/C/O powders. These powders were composed of crystalline TiO2 nanograins mixed with C. Annealing under argon enabled the formation of TiC through the carburization of TiO2 by free C. The final TiC mean grain size was about 80 nm. Zr/O/C powders were prepared from a solution of zirconium butoxide and were composed of ZrO2 crystalline nanograins and free C. The same thermal treatment as for TiC, but at higher temperature, showed the formation of crystalline ZrC with a final mean grain size of about 40 nm. These two liquid routes of nanoparticles synthesis are also compared to the very efficient gaseous route of SiC nanopowders synthesis from a mixture of silane and acetylene