Effect of binder types on the properties of the mullite fibrous ceramics prepared by TBA-based gel-casting method

Mullite fibrous ceramics with different types of binders (silica particles, SiO2-B2O3 mixture and silicon particles) were successfully fabricated by a TBA-based gel-casting. The influence of the above three types of binder on the microstructure and properties of the ceramics were investigated. The results show the resource of the binders played an important role in tailoring the inner structure of the ceramics, consequently influencing the product properties. All products showed high porosity, low density and low thermal conductivity, attributed to the special 3D fibrous skeleton structure. The products with silica as binder sintered at 1500 degrees C exhibited relatively low compressive strength because of the high melting point of the silica particles. On the contrary, the products with silicon and SiO2-B2O3 as the binder sintered at 1500 degrees C showed higher compressive strength owing to the low viscosity of the binders during the sintering process. Compared with the products SiO2-B2O3 as the binder, the products with silicon as the binder was more suitable for being used in the high-temperature environment (above 1500 degrees C), since the silicon could transform into the silica phase with high melting point. Besides, with the increase of the silicon content, the compressive strength and the thermal conductivity of the products increased gradually.