Microstructure observation of β-sialon-15R ceramics synthesized from aluminum dross

Fully dense β-sialon-15R multiphase ceramics were synthesized by hot pressing sintering using aluminum dross as raw material. Transmission electron microscopy (TEM) was used to study the microstructure, notably for the impurity and glass phase. The results show that β-sialon grains are generally equiaxed, and 15R AlN polytypoid grains show a fibre-like morphology. The main impurity phase is Fe5Si3. High resolution electron microscopy (HREM) results confirm the interface between β-sialon grains and/or 15R grains to be clean in the sample synthesized at 1750 °C, and the glassy phase only exist in triple junctions and pockets. AlN polytypoids in the multiphase ceramics provide a path to reduce the glass phase formed from the oxide impurity in aluminum dross.