Abstract: In order to improve the high value-added utilization of fly ash, mullite whisker precursor reinforced urchin-like mullite ceramic materials were in-situ prepared by the solid-phase method by using aluminum hydroxide and fly ash hollow sphere as aluminum and silicon source of urchin-like mullite precursor, aluminum hydroxide and fly ash as the aluminum and silicon source of mullite whisker precursor reinforcing agent, AlF₃ and V₂O₅ as the whisker accelerator and sintering aid severally. The effects of the ratio of reinforcing agent to the urchin-like mullite precursor (the mass ratio were 3:7, 4:6, 5:5, 6:4, and 7:3 respectively) on the properties, phase composition, and microstructure of the prepared mullite ceramic materials were studied. The results show that when the ratio of reinforcing agent to the urchin-like mullite precursor change from 3:7 to 7:3, the crystal phase formed in the sample is mullite, and the interior of the material is denser, the bulk density and compressive strength gradually increase, total porosity gradually decrease. The introduction of the reinforcing agent improves the linear change rate and thermal shock resistance, but reduces the reheating linear change rate of materials, and the residual compressive strength and residual strength ratio first increase and then decrease. The prepared mullite materials with better comprehensive properties can be obtained when the mass ratio of the reinforcing agent to urchin-like mullite precursor is 6:4.

Key words: fly ash, mullite whisker precursor, urchin-like, in-situ reinforcement