Mullite whiskers derived from coal fly ash

Alumina-deficient (Al2O3/SiO2 = 1.12, molar ratio), orthorhombic mullite whiskers with a diameter of 0.6-1.8 mu m (aspect ratio > 30) have been manufactured by firing compacts of coal fly ash and NH4Al(SO4)(2)center dot 12H(2)O powders, with a small addition of NaH2PO4 center dot 2H(2)O, at 1300 degrees C for 10h. The manufacturing process, the morphology, and structure of the whiskers are described. (c) 2006 Elsevier B.V. All rights reserved.