Phase Formation and Process Analysis of SiC-Al2O3-Al6Si2O13 Composite Powders via Carbothermal Reduction of Fly Ash at 1550℃

摘要

Silicon carbide (SiC)-alumina (Al2O3)-mullite (Al6Si2O13) composite powders were successfully synthesized at 1550℃ for 5h via carbothermal reduction reaction, and the effects of various mass ratios of active carbon to fly ash (0.38, 0.44 and 0.58)on the phase compositions and microstructures of products were investigated, and the formation process of the powders was also analyzed in detail.The products mainly consist of β-SiC, a-Al2O3, Al6Si2O13 and FeSi.Increasing carbon content favors the decomposition of Al6Si2O13 and formation of SiC.The average particle sizes of β-SiC and α-Al2O3 as well as Al6Si2O13 are about 1μm and 5-10μm, respectively.The formation process of SiC-Al2O3-Al6Si2O13 powders includes the decomposition of mullite in fly ash and formation of SiC.