Preparation of mixtures of silicon oxynitride and silicon nitride by the reaction of calcium silicide with ammonium chloride

Silicon nitride and silicon oxynitride materials have great potential for high‐temperature, load‐bearing applications because of their high strength, high thermal shock resistance and good oxidation resistance. The subnitride (Si3N)n formed by the known reaction of CaSi2 with ammonium halides is shown here to react with nitrogen providing a new route to, for example, silicon nitride fibers (see figure). magnified image