Fabrication and characterization of mullite-whisker-reinforced lightweight porous materials with AlF3·3H2O

Mullite-whisker-reinforced lightweight porous materials were fabricated by the particle stabilization method using fly ash and calcined bauxite as raw materials, and AlF3·3H2O as an additive. The effect of AlF3·3H2O on the phase composition, volume density, porosity, microstructure, mechanical performance, and heat conductivity of mullite-whisker-reinforced lightweight porous materials was explored. With an increase in the AlF3·3H2O content, the linear shrinkage, volume density, compressive strength, flexural strength, and heat conductivity of lightweight porous materials increased and their porosity decreased. When the AlF3·3H2O content was 9 wt%, flexural and compressive strengths of lightweight porous material samples with a porosity of 72.3% and an average whisker length of ∼19.2 μm were 17.8 and 31.0 MPa, respectively, and the heat conductivity was maintained at a minimal value of 0.092 W (m K)−1.