Si-C-N COMPOSITE POWDERS, THERMAL PLASMA SYNTHESIS AND CHARACTERIZATION

Nanoscale Si-C-N composite powders with mean particle size less than 100 nm were synthesized by the RF induction plasma. Reactions of methylated silanes (Si(CH₃)₄ or SiCl₃CH₃) and NH₃ or between nonmethylated silanes (SiCl₄ or SiH₄), C₂H₄, and NH₃ were studied. Both the chemical composition and the morphology of nanoscale Si-C-N composites can be controlled by precursors as well as processing. Crystalline phase is mainly β-SiC, but sometimes a change of the lattice constant suggests a nitrogen incorporation into the SiC lattice. Annealing of the composite powders results in nanostructured powders, containing β-SiC as well as α-Si₃N₄ and β-Si₃N₄. Additionally temperature fields of the RF induction plasma were determined theoretically as well as experimentally.