A Catalytic Process for Mullite Whiskers

Abstract

Mixtures of alumina and silica react with SiF, above 600°C to form fluorotopaz. Pyrolysis of fluorotopaz gives a stoichiometric yield of interlocked whiskers of mullite and SiF,, which is recovered for reuse. The diameter of whiskers (aspect ratio -15) can be controlled from a maximum of -100 pm to less than 1 pm.

Preparation of mullite whiskers from topaz decomposition

“…So far, whiskers with 50 -200 Am are reported growing on alumina particle [5], which means they are not free whiskers. Moyer made a whisker with 100 Am, but with the aspect ratio of less than 15 [7]. More usually, they possess an average length of less than 30 Am and aspect ratio of less than 35 with a rare exception to 100 Am of length.…”

Formation mechanism and microstructure development in acicular mullite ceramics fabricated by controlled decomposition of fluorotopaz

“…[1][2][3][4] Mullite has been selected as a target material because of its ability to crystallize in the form of long needles and its well known stability at high temperature, high corrosion resistance, and high strength. The presence of mullite in sintered porcelain bodies has been known for a long time.…”

Structured reactors for enzyme immobilization: advantages of tuning the wall morphology

“…The Dow Chemical Company has developed a highly porous acicular mullite ceramic, ACM, having a unique open microstructure as shown in Fig. 1 (Moyer and Hughes, 1994;Wallin et al, 2001). By controlling the synthesis conditions, the mean pore size can be tailored on the micron length scale.…”