Effect of mullite fiber content on the microstructure and properties of porous mullite fiber/silica composite

Porous mullite fiber/silica composite was successfully fabricated by a TBA-based gel-casting, and the influence of mullite fiber content on the composite microstructure and properties were investigated. The results show that the mullite fiber content played an important role in tailoring the microstructure of the composite, consequently influencing the sample properties. The composite fabricated with high fiber content showed a porous fibrous structure with mullite fibers as the fiber skeleton and silica as the binder, and exhibited a low density, high porosity, excellent elasticity and low thermal conductivity. On the contrary, the sample fabricated with low fiber content possessed a high density and high strength due to its dense microstructure which is similar with that of the fiber reinforced ceramic matrix composite.