Processing of Mullite Whiskers from Kaolin
Mullite whiskers have been manufactured by firing compacts of kaolin, Al2(SO4)3 and (NH4)2SO4 powders, with a small addition of Na2SO4, in air at 1400o C for 15 h. From the batch composition of Al2O3/SiO2 = 0.7, molar ratio, alumina-deficient (Al2O3/SiO2 = 1.02, molar ratio), orthorhombic mullite whiskers with an aspect ratio of >30 (0.2-0.4 μm in diameter) were obtained. With increasing Al2O3/SiO2 molar ratio, the size and aspect ratio of the mullite whiskers decreased.
Deliang Zhang, Kim Pickering, Brian Gabbitas, Peng Cao, Alan Langdon, Rob Torrens and Johan Verbeek
B.M. Kim et al., "Processing of Mullite Whiskers from Kaolin", Advanced Materials Research, Vols. 29-30, pp. 203-206, 2007