Effect of temperature and magnesia on phase transformation kinetics in stoichiometric and non-stoichiometric cordierite ceramics prepared from kaolinite precursors Smail Lamara 1,2 • Djaida Redaoui 1,2 • Foudil Sahnoune 2,3 • Nouari Saheb 4 Received: 24 July 2018 / Accepted: 13 November 2018 Ó Akade ´miai Kiado ´, Budapest, Hungary 2018 Abstract The influence of temperature and magnesia content on the formation of phases and their transformation kinetics in stoichiometric and non-stoichiometric cordierite ceramics prepared from Algerian kaolinite precursors was investigated. High-temperature X-ray diffraction was used to study the formation of phases and their transformations. Non-isothermal differential thermal analysis was used to determine kinetic parameters for the formation of l and a cordierite. Activation energies were calculated by Kissinger, Boswell, and Ozawa equations. The Augis–Bennett and Matusita equations were used to calculate the mode of crystallization (n) and dimension of growth (m) parameters, respectively. The synthesized materials showed similar phase transformations, which finally led to the formation of cordierite in stoichiometric kaolinite– magnesia mixture, and cordierite along with other phases in kaolinite–magnesia mixture containing excess magnesia. The activation energy for the formation of a cordierite was higher than that of l cordierite. Energies of formation of l and a cordierite phases in the non-stoichiometric samples were higher than those in the stoichiometric sample. The activation energy was less sensitive to the calculation method; however, it changed significantly with MgO content. Activation energies between 573 and 964 kJ mol -1 were obtained. Magnesia changed the crystallization mode and crystal growth dimension. The kinetic parameters n and m, for the formation of l or a cordierite, had values between 2 and 3. Keywords Kaolinite Á Magnesia Á Cordierite Á Solid-state reaction Á Phase transformation kinetics Introduction Cordierite phase, with 2MgOÁ2Al 2 O 3 Á5SiO 2 and Mg 2 Al 4 Si 5 O 18 chemical composition and chemical formula, respectively, forms when Al 3? and Mg 2? cations diffuse in the SiO 2 structure. It is an important phase in the MgO– Al 2 O 3 –SiO 2 system and is characterized by a narrow sin- tering temperature range. Cordierite has relatively low theoretical bulk density of 2.53 g cm -3 , high melting point of 1470 °C, very low coefficient of thermal expansion (1–2 9 10 -6 C -1 ), high electrical resistivity ( [ 10 12 X cm), low thermal conductivity, high stability in harsh environments, and acceptable mechanical properties [1, 2]. Because of their thermal, electrical, and mechanical properties, cordierite ceramic materials are extensively used in many applications [1–7] including packaging, geobarometry and geothermometry [6], and thermal insu- lation [7]. Additionally, they are good candidates for making refractory and high thermal shock resistance products, components for turbine heat exchangers, and catalysts’ supports in cars [1–5]. Although cordierite is rare in earth [8], it can be syn- thesized from different raw materials by different methods [9–17]. Readily available natural materials or minerals & Nouari Saheb nouari@kfupm.edu.sa 1 Physics and Chemistry of Materials Lab, Department of Physics, University Mohamed Boudiaf of M’sila, M’sila, Algeria 2 Physics Department, Faculty of Science, University Mohamed Boudiaf of M’sila, 28000, M’sila, Algeria 3 Research Unit On Emerging Materials (RUEM), University Ferhat Abbas of Se ´tif 01, 19000 Se ´tif, Algeria 4 Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia 123 Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-018-7923-2