In-Situ Synthesis of (O′+β)-Sialon/Mullite Composite Materials from Coal Gangue

Abstract

(O′+β)-sialon/mullite composite materials were synthesized by an in-situ carbothermal reduction nitridation method, with coal gangue and carbon black as raw materials. The influences of temperature and carbon content on the phase composition and microstructure of the pre-synthesized materials were investigated by XRD and SEM. The effects of variation in the phase composition, the microstructure on the bulk density, the bending strength of the pre-synthesized materials were investigated in detail. The results indicated that increasing temperature and carbon content benefit the generation of O′-sialon and β-sialon. The (O′+β)-sialon/mullite composite material can be synthesized at 1400°C (6 h) ∼ 1500°C (6 h). The generative process including the formation of β-sialon, O′-sialon and the conversion process from β-sialon to O′-sialon. The O′-sialon and β-sialon in the synthesized materials have needle-like and pillar structures, respectively. Given all that, the (O′+β)-sialon/mullite composite material prepared by coal gangue and carbon black contributes to solving the problem of the recycling of coal gangue, and high-performance composite materials can be obtained.