Preparation of mullite whisker skeleton porous ceramic

Sillimanite whisker skeleton porous ceramic was firstly prepared by an appropriate firing process from kaolinite and ammonium hexafluoroaluminate (ABA) as raw materials, then mullite whisker and corundum were produced by firing the sillimanite whisker skeleton at 1400 degrees C. Effect of firing system on the sillimanite whisker skeleton formation was examined in detail. A series of complex gas phase reactions between the kaolinite and ammonium hexafluoroaluminate (AHA) caused the sillimanite whisker skeleton formation in the ceramic body. The experimental results show that one-step firing process with fast heating rate leads to the hexagonal shaped alpha-Al2O3 platelet forming, but the slow heating rate or two-step firing processes can completely cause the whisker skeleton structure generation. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.