Characterization of Aluminous Clays from Tamilnadu

Abstract

Plastic aluminous clays are abundantly available in Tamilnadu. However, at present the utilization of these clays is very low due to lack-of detailed characterization. In the present work, the green and fired characteristics of clays obtained from three different locations in Tamilnadu (Udayarpalayam, Panruti and Neyveli) have been investigated to assess their potential use as raw materials. Physical properties, plasticity index, particle size analysis, chemical analysis, X-ray diffraction and thermal analysis of these clays have been carried out. Physical properties such as density, bending strength, X-.ray diffraction and scanning electron microscopy of the fired samples have also been carried ouf. The properties of the above three clays are compared with each other. The results show that these clays are plastic in nature co_.,,taining a moderate amount of impurities with high alumina contetlt. IntroductionClays are· found ·in. many locations in Tamilnadu and most of them have not been fully mapped and characterized. Clay samples from Neyveli and Panruti of Cuddalore district and Udayarpalayam of Aryalur district have been selected for systematic investigations. A detailed examination of the physical and chemical characteristics of the clays as well as their behaviour at high temperatures has been made. Although a few research papers 1 -3 are available on Neyveli clay, they have been focused only on commercial aspects. Viswabaskaran et a/. 4 showed that Neyveli clay exhibits the best mullitization behaviour when sintered with reactive alumina and hence, is a useful material for technical applications such as membrane supports, electronic substrate and tubes for high temperature applications. 5 The mullite membrane support made by using the Neyveli clay showed small pores with narrow pore size distribution and excellent strength. The low dielectric constant (7.35) and low thermal expansion (3.4 x 1 o-s/°C) make the Neyveli clay based mullite suitable for electronic substrate applications. 5 Neyveli clay bed is present with the lignite bed and the thickness varies from 1 .5 to 2 m and the total quantity of the clay has been