Formation of anorthite containing cordierite materials through reaction sintering kaolin, MgO and CaO precursors

• Main Authors: Lamara Smail, Redaoui Djaida, Sahnoune Foudil, Heraiz Menad, Saheb Nouari
• Format: Article
• Language: English
• Published: International Institute for the Science of Sintering, Beograd 2020-01-01
• Series: Science of Sintering
• Subjects: clays; mgo; cordierite; sintering; kinetics
• Online Access: http://www.doiserbia.nb.rs/img/doi/0350-820X/2020/0350-820X2002135L.pdf

The effect of CaO on cordierite formation from kaolin-MgO-CaO powder mixtures, milled for 5 h and reaction sintered for 2 h in the temperature range 900-1400°C, was investigated. Phases formed in the developed materials were characterized by x-ray powder diffraction method (XRD) and Raman spectroscopy. Non-isothermal differential thermal analysis (DTA) and thermogravimetric (TG) experiments were performed from room temperature to 1400°C, at heating rates from 20 to 40°C/min. Activation energies were determined using Kissinger method. It was found that sintering the stoichiometric kaolin-magnesia mixture led to the nucleation and growth of monolithic cordierite; while cordierite along with anorthite were present in the other two samples where 4 or 8 wt% of CaO was added. The increase in CaO decreased cordierite formation temperature and increased the activation energy, which ranged from 445 to 619 kJ/mol for μ-cordierite and from 604 to 1335 kJ/mol for α-cordierite.