Nano-Scale Cordierite Glass-Ceramic from Natural Raw Materials with Different Fluoride Additions

• Published in: SILICON 2020-05, Vol.12 (5), p.1051-1057
• Main Authors: Eldera, Samah S., Alharbi, Omar A., Rüssel, C., Al-wafi, Reem, Hamzawy, Esmat M. A.
• Format: Article
• Language: English
• Subjects: Aluminum fluorides; Chemistry; Chemistry and Materials Science; Cordierite; Crystallization; Environmental Chemistry; Fluorine; Glass ceramics; Heat treatment; Inorganic Chemistry; Kaolin; Lasers; Magnesite; Magnesium carbonate; Magnesium fluorides; Materials Science; Microhardness; Optical Devices; Optics; Original Paper; Photonics; Polymer Sciences; Raw materials; Thermal expansion
• ISSN: 1876-990X; 1876-9918
• DOI: 10.1007/s12633-019-00200-x

Stable cordierite glass-ceramics were prepared from natural kaolin, silica sand and magnesite as raw materials. Furthermore the effect of fluorine additions was tested by addingAlF 3 or MgF 2 tothe glass composition. Stable cordierite was crystallized in all glass-ceramic samples during thermal treatment at temperatures in the range from 900to 1200 °C. In the microstructure cordierite, crystals of sizes 15to 50 nm in parent sample and 500 nm to 1 μm in the sample prepared using AlF 3 as raw material were observed, while in the sample prepared from MgF 2 as raw materials, the crystal sizes were > 1 μm. The coefficients of thermal expansion of the present cordierite glass-ceramic (CTE) were found to be, 1.14 × 10 −6  K −1 (100–300 °C) for the parent glass and 4.93 × 10 −6  K −1 (100–500 °C) for the glass-ceramic containing high AlF 3 sample.Also, the microhardness values were between 5. 20 and 6.34 GPa for glass-ceramic samples. The densities of cordierite glass-ceramics increased from 2.07 g/cc in the parent sample to 2.54 g/cc and 2.58 g/cc in AlF 3 and MgF 2 containing samples, respectively. The resultant material can resist the temperature up to 1200 °C.