Fabrication and morphology control of high strength lightweight mullite whisker network

This work presents a simple approach to produce controlled mullite whisker network structure. Mullite whisker networks were facilely prepared by direct sintering of coal fly ash, bauxite and kaolin in BaCO₃-potash feldspar-pyrolusite-talcum catalytic system at 1350 °C. Controlled mullite whiskers were obtained with about 200 nm in diameter and 3 μm in length by controlling the rate of Al₂O₃ diffusion through feldspar addition in catalytic system. Morphology evolution process and growth characteristics of mullite whisker networks were further investigated using scanning electronic microscope (SEM) and their possible fabrication mechanism were also investigated. The optimum mullite whisker network structural material exhibits some attractive properties such as high strength (199.89 MPa), low density (1.51 g cm⁻³) and low acid solubility (2.63 wt%). These results demonstrate an effective method to prepare large-scale mullite whisker network with potential applications in producing ceramic proppants.