Hs. Tripathi et al., Synthesis and thermo-mechanical properties of mullite-alumina composite derived from sillimanite beach sand: effect of ZrO2, CERAM INT, 27(8), 2001, pp. 833-837
A mullite-alumina composite was developed by reaction sintering of silliman
ite beach sand and calcined alumina. ZrO2 (2-6 wt.%) was added as additive.
The raw materials and additive were mixed, attrition milled and sintered i
n compacted form at 1400-1600 degreesC with 2 h soaking. The effect of ZrO2
on the densification behaviour, thermo-mechanical properties and microstru
cture was studied. It was found that addition of ZrO2 slightly retards the
densification process. All the samples achieved their highest bulk density
at 1600 degreesC. Thermo-mechanical properties of the sintered samples are
not effectively altered by the presence Of ZrO2. ZrO2 containing samples al
ways show better resistance to thermal shock than the ZrO2 free samples. Sc
anning electron micrography shows that ZrO2 occupies both an intergranular
and intragranular position in the mullite matrix. The mullite formed at 160
0 degreesC is mostly equiaxed in nature that suggests densification mainly
occurs through solid state sintering. (C) 2001 Elsevier Science Ltd and Tec
hna S.r.l. All rights reserved.