Preparation and Characterization of p-sialon Ceramics from High Aluminium Fly Ash via Carbothermal Reduction-nitridation

摘要

In this work, p-sialon ceramics were prepared from high-aluminium fly ash via carbothermal reduction-nitridation (CRN) and the physicochemical properties of the materials such as bulk density, apparent porosity, water absorption and flexural strength were also discussed. The results showed that the percentage of P-sialon phase in the product decreases as the temperature increases from 1400℃ and the weight of the sintered specimen experienced an increase during 1350℃～1450℃ due to the nitridation reactions, and followed by a gradual decrease till 1550℃ for the decomposition of β-sialon. It is indicated that the optimum sintering temperature to obtain the highest yield of p-sialon ～93% lies in 1400℃～1450℃. The SEM images revealed that the prepared (3-sialon sintered at 1400℃ were mainly in shape of elongated prisms, typically ～5μm in length and 0.5～1 μm in width. As the temperature increased to 1500℃ and above, β-sialon decomposed and the new phases of SiC and AlN were formed at 1550℃ as confirmed by XRD.