Porous Cordierite Ceramics with Illite Clay Additive: Synthesis and Properties Maris Rundans1*, Gaida Sedmale1, Liga Grase1 1 Institute of Silicate Materials, Riga Technical University, Paula Valdena 3/7, LV-1048, Riga, Latvia (*email: maris.rundans@rtu.lv) Porous cordierite ceramics materials are widely employed due to their high temperature stability which is a result of negative lattice expansion in crystallographic “c” axis direction [1] which leads to average reported value of coefficient of thermal expansion being 1-2·10-6 °C-1 [2]. When sufficiently high mechanical strength can be achieved, such materials are widely used substrate material for catalytic processes, refractory material and supports for high-temperature applications. In this work porous cordierite ceramics have been prepared by using local resource of carbonate-containing illite clays as main additive. The changes in porosity, bulk density, compressive and flexural strength, coefficient of thermal expansion as well as crystalline phase content have been studied. The obtained porous ceramics samples have macroscopic pore structure with total porosity being in 60-70 vol% range and bulk density – 1.10-1.25 g/cm3. Crystalline phase content is dominated by cordierite (above 90 %) with small amount magnesium spinel serving as secondary phase. Compressive and flexural strength test result analysis shows that the increase of synthesis temperature and content of illite clay leads to samples with lowered mechanical performance. However, the samples made with clay additive of higher carbonate content led to increase in compressive and flexural strength of material by about 30% in comparison to samples with lower carbonate content clay additive. Increased amount of carbonate content in clay additive, however, also increased samples’ coefficient of thermal expansion. Keywords: cordierite, synthesis, ceramics 1. J. Zhou, Y. Dong, S. Hampshire and G. Meng, Appl. Clay Sci. 52, 328-332 (2011) 2. S. Kurama and H. Kurama, Ceram. Int. 34, 269-272 (2008)