Silicon Nitride Rapid Decomposition
for Ceramic Nanopowder Manufacturing¹

D. Kata and J. Lis

AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow, Poland

Abstract—Rapid decomposition of silicon nitride at high temperatures has been successfully used to manufac-
ture ceramic nanopowders in the Si–C–N and Si–O–N systems. For powder processing, the solid combustion
called self-propagating high-temperature synthesis (SHS) was realized and investigated. The well-mixed pow-
dered reactants were placed in porous container; then, the reaction was locally ignited and combustion was
propagated in a self-sustaining regime, achieving temperatures of over 2000°C. In all these experiments, com-
bustion propagated with the formation of the transient Si₃N₄ phase resulted in either SiC or Si₂ON₂ nanosized
grains. To elucidate the role of the decomposition of silicon nitride in the formation of nanosized products, ther-
modynamic data, temperature profiles, morphology (SEM, TEM), dispersion (BET) and phase composition
(XRD) of the products were evaluated. It was found that, in both Si–C–N and Si–O–N systems, silicon nitride
forms transiently at early stages of combustion because of thermodynamic and kinetic considerations. Finally,
it was demonstrated that the technology of silicon carbide and silicon oxynitride nanopowders achieved by the
decomposition of Si₃N₄ is very efficient compared to other conventional techniques. The powders obtained are
well sinterable and, after further processing, can be used in a wide range of applications, such as refractory
materials, ceramic armor, elements of chemical equipment, etc.

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