Transactions of the INDIAN CERAMIC SOCIETY Vol. 60 2001
Studies on Cordierite-Mullite Body - Part II : Effect of
Sillimanite Sand in a Cordierite Composition
K. N. Maiti and K. C. Singh
Pages : 167-171
DOI : 10.1080/0371750X.2001.10799996
Abstract
Beach sand sillimanite was substituted for china clay and fireclay
grog in a standard cordierite body mix containing 60% china
clay, 20% fireclay grog (IS-6 grade) and 20% talc. The specimens
were fired at different temperatures ranged from 1200 to 1340 C
with 2 h dwelling time at respective peak temperatures. The
addition of 40 wt% sillimanite in the standard composition was
found to improve the mechanical properties and to reduce the
coefficient of thermal expansion from 25.7 x 10-7 to 20.43 x 10-7
at 500C and 25.20 x 1 o-7 to 21.34 x 10-7 at 1000 C. The reduction
in the coefficient of thermal expansion value of the body
mix containing 40 wt% sillimanite was due to the presence of
cordierite and mullite and I or sillimanite phases in the composition.
The final body also showed enhanced fired .strength from
147.67 kg.cm· to 241.90 kg.cm-2 after firing at 1340 C. The thermal
shock resistance of the developed body mix containing 40
wt% sillimanite. measured in terms of percent loss of MOE after
repeated thermal shock at gradually enhanced temperatures in
water quenching, was found to be more than two times higher
than that of the standard cordierite composition.