1School of Chemistry, The University of Sydney, Sydney NSW 2006, Australia
2Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
3Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
4Department of Chemistry, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
Adv. Mater. Lett., 2020, 11 (12), 20121585
Publication Date (Web): Nov 09, 2020
Copyright © IAAM-VBRI Press
A low thermal diffusivity SiO2-based ceramic was fabricated by sintering Malaysia agricultural waste rice husk at 800 °C. This paper presents the effect of sintering temperatures on the phase transformation, microstructure and thermal diffusivity of rice husk ash (RHA) as a thermal insulating material. A series of SiO2-based ceramics were fabricated from rice husk via two sintering stages. Rice husk was pre-sintered at 700 °C and then ground into powder. The RHA powder was compacted into pellets and then re-sintered at a single temperature between 700 and 1400 °C. Sintering of the RHA induces phase transformation from amorphous silica to crystalline α-cristobalite, α-tridymite and β-tridymite. The thermal diffusivities of RHA were evaluated using the laser flash analysis technique. The results indicate RHA-800 °C has the lowest thermal diffusivity, which is 0.17 ± 0.1 mm2 s−1 at 25 °C. The RHA particle morphologies were observed using a field-emission scanning electron microscopy. Low-frequency vibrational modes of silica such as lattice vibration were investigated using Fourier-transform infrared spectroscopy technique. X-ray fluorescence result indicated that RHA-800 °C contains ~90 wt % of SiO2.
Rice husk ash, silica, thermal diffusivity, thermal insulator.