Synthesis of nano size dispersed silicon carbide particles by firing inorganic-organic hybrid precursors

摘要

Inorganic-organic precursor gels for nano size dispersed SiC particles were prepared by simultaneous condensation of the liquid mixture of ethyl silicate, ethyl borate and water soluble phenol resin. After drying the gels under reduced pressure and pyrolysis at 1273K, the gels were converted into the precursors consisting of metal oxide and carbon. The precursor yielded ultrafine silicon carbide particles in nanocrystalline form with carbothermic reduction beyond 1773K. The isothermal TG curves during the carbothermic reduction revealed that conversion processes of the precursors into SiC fitted on the kinetic equation based on crystal growth in homogeneous media. This should be due to the quasi- homogeneous microstructure in the hybrid gels and in the precursors obtained with pyrolysis. The excess carbon and addition of boron into the precursors were effective to obtain small and uniform size of SiC particles.