Cordierite-Based Ceramics from Coal Fly Ash for Thermal and Electrical Insulations

• Published in: SILICON Vol. 13; no. 2; pp. 327 - 334
• Main Authors: Tabit, Kamal, Hajjou, Hanaa, Waqif, Mohamed, Saâdi, Latifa
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2021; Springer Nature B.V
• Subjects: Bulk density; Ceramics; Chemistry; Chemistry and Materials Science; Coal; Compressive strength; Cordierite; Densification; Differential thermal analysis; Environmental Chemistry; Fly ash; Fourier transforms; Infrared analysis; Inorganic Chemistry; Insulators; Lasers; Magnesium oxide; Materials Science; Mechanical properties; Optical Devices; Optics; Original Paper; Photonics; Polymer Sciences; Porosity; Sintering (powder metallurgy); Superconductors (materials); Thermal conductivity; Coal fly ash; Cordierite; Dielectric; Thermal insulator
• ISSN: 1876-990X; 1876-9918
• DOI: 10.1007/s12633-020-00428-y

In the present study, coal fly ash was used as the main starting material (80.74 wt.%) in the production of the cordierite-based ceramics by benefiting from its high contents of silica and alumina. The phase evolutions and the properties of sintered materials in the range of 900–1200 °C were investigated by thermogravimetric and differential thermal analyses (TG-DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), compressive strength, bulk density, and apparent porosity. The results revealed that the increase in firing temperature from 900 °C to 1200 °C induced the transformation of coal fly ash components and the magnesium oxide into cordierite with high purity. The formation of the cordierite at 1200 °C involved the densification of the ceramic body and the decrease in the apparent porosity to 22%. The compressive strength was improved with the increase in sintering temperature and reached a maximum of 128 MPa. The obtained cordierite-based ceramics exhibited a thermal conductivity of 1.12 W/m.K, along with high mechanical properties, which promoted its applications for thermal insulators. Also, the dielectric constant (ε = 9.5 at 1 MHz) measurements indicated that the cordierite-based ceramics from coal fly ash can be useful for electrical insulators.