Preparation of Sialon powder from coal gasification slag

Abstract

X-ray fluorescence spectrometry (XRF), X-ray powder diffractometry (XRD) and scanning electron microscopy (SEM) were used to characterize the chemical composition, phase constituent and microstructure of the coal gasification slag. Sialon powders were synthesized by carbothermal reduction and nitridation using the coal gasification slag as raw materials. The experimental results showed that glass and amorphous carbon were the main phases, quartz and calcite as minor crystalline phases were also presented in porous coal gasification slag. Main constituents of coal gasification slag were SiO₂, Al₂O₃, CaO and residual carbon. Sialon powder with Ca-α-Sialon as main crystalline phase can be synthesized when coal gasification slag powders were reduced and nitrided at 1500 °C for 9 h using nitrogen flow of 500 ml/min. The coal gasification slag is a valuable and economic starting material for preparing Sialon powders.

Keywords

coal gasification slag / characterization / microstructure / Sialon / carbothermal reduction and nitridation

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