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The effect of excess MgO, 2.0–4.0 mol ratios on the crystallization behavior and purity of μ‐cordierite was investigated using X‐ray diffraction (XRD), differential thermal analyzer, and TGA. Quantitative XRD, the Rietveld technique, was carried out using the HighScore Plus software. The glass crystallization process route was used with talc and kaolin as the main raw materials and compensated with MgO, Al2O3, and SiO2 accordingly. The crystallization temperature of the glasses decreased as a function of the MgO mole ratio. Less than 2.8 mol MgO increased the formation of α‐cordierite up to 94 wt%. However, above 2.8 mol ratio, the forsterite phase started to appear, together with mullite, μ‐cordierite, and spinel.

Densification and crystallization behaviors of nonstoichiometric cordierite synthesized from minerals through the glass route are reported in this paper. DTA of glass powder was conducted under isothermal and nonisothermal conditions. The activation energy was calculated from the dilatometry test at constant heating rate by using Arrhenius equation to observe their densification behavior. The densification and crystallization of composition with MgO mole ratio of 3.4 and 4.0 below 9001C were confirmed using nonisothermal DTA and dilatometry. However, samples below 2.6 mol MgO were not fully densified and crystallized when isothermally heated for 2 h. When MgO content was increased 2.0-3.0 mole ratio, the activation energy for densification decreased, but it increased for MgO mole ratio ! 3.4.

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