SYNTHESIS OF NANOMATERIALS VIA PRECERAMIC POLYMERS

Materials with novel properties are obtained when the constituent phas e morphology is reduced to nanometer dimensions. In this emerging area , investigations have involved the use of organometallic precursors fo r nanomaterials. The conversion of an organosilazane aerosol precursor resulted in ultrafine preceramic and ceramic particles. Experimentall y, aerosols of an organosilazane precursor, [CH3SiHNH]n with n = 3 or 4, were injected into (i) the beam of an industrial laser, and (ii) a hot furnace, to obtain Si3N4/SiC nanoparticles. One critical feature e xamined, when the synthesis was performed using laser radiation, was t he rapid condensation of molecular species from the laser plume. This process involved a 3-dimensional cross-linking reaction to form precer amic nanoparticles. Subsequent thermal treatment of this preceramic po lymer resulted in the formation of Si3N4/SiC nanoparticles. When the s ynthesis was carried out using a thermal reactor, nanoparticles of Si3 N4/SiC could be obtained in an integrated process. A model has been fo rmulated to determine the laser plume temperature, the cooling rate, a nd the particle size. A similar model has also been investigated for t he thermal reactor synthesis process.