Preparation and characterization of mullite microspheres based porous ceramics with enhancement of in-situ mullite whiskers. Issue 12 (15th August 2019) - Yi, Ping
Abstract: High-strength insulating ceramic materials were prepared using lightweight mullite microspheres with dense surfaces and high internal porosity as the main raw material and silica sol as a binder. The effects of AlF3 ·3H2 O content on the in situ formation and growth of mullite whiskers were analyzed by X-ray diffraction and scanning electron microscopy. The obtained results showed that mullite whiskers were formed in large quantities at 1200 °C using AlF3 ·3H2 O and V2 O5 as additives; their optimal growth was observed at 4 wt% AlF3 ·3H2 O and 1 wt% V2 O5 . The apparent porosity of the produced specimens was 39%; the MOR and CCS of the specimens were 31 and 152 MPa, respectively; the HMOR at 1300 °C was 11.32 MPa; and the thermal conductivity at 900 °C was 0.783 W m −1 K −1 . The staggered whisker network structure formed between mullite microspheres not only improved the mechanical properties of the material, but also refined its pore size, reduced the thermal conductivity, and enhanced the thermal insulation properties.