Phase and Microstructural Evolution, and Densification
Behaviour of Kaolin Powder Compacts |
Muhammad Fahad,a, * Umair Faridb and Yaseen Iqbalc
pages : 47-52
DOI : 10.1080/0371750X.2016.1144485 |
Abstract |
Two types of kaolin clay samples of different origins were studied using X-ray
diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy and
thermogravimetric/differential thermal analysis. Mineralogical and morphological
characteristics of die-pressed kaolin samples were investigated. Kaolinite was
identified as the major mineral phase; however, other minerals, e.g. illite and quartz
were also present as subordinates. The transformation heats during heating were
quantified from DTA measurements and phase changes were followed by XRD
analyses. The present results indicated a series of phase transformations as the kaolin
was fired at elevated temperatures. The formation of mullite was detected by XRD at
a temperature as low as 1100oC. Microstructural evolution investigations showed
that mullite needles were formed within the powder compacts during sintering. Size
and aspect ratio of the mullite grains increased with the increase of firing temperature.
The powder compacts showed anisotropic shrinkage after sintering, mainly due to
preferred orientation of the kaolin flakes within the powder compacts. The density
was found to be increasing with increase of firing temperature until 1300oC.
[Keywords: Differential thermal analysis, Kaolinite, Microstructure, Mullite, Sintering
temperature] |
Full text : Subscribe to Download Full Text |
[Go Back] |
|