Phase and Microstructure Evolution of Mullite Synthesized from Coal Gangue and γ-Al2O3

摘要

Mullite with puncheon-like grains was synthesized by sintering the mixtures of coal gangue and γ-Al2O3 at 1400 °C～1550 °C for 4h.The phase and microstructure evolution of the mullitization behavior were investigated by XRD,SEM and EDS.Phases of the sintered specimens were mullite,corundum and cristobalite at 1400 °C to 1450 °C.Increase of temperature would enhance mullitization,and total consumption of cristobalite occurred from 1500 °C upward.The in-situ produced primary mullite from gangue upon heating can be seeds for the growth of evenly dispersed mullite puncheons.Specimen sintered at 1550 °C consists of puncheons with an aspect ratio of 2～4,regionally forming an interlocking structure.