Banjuraizah Johar
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Banjuraizah Johar
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Banjuraizah, Johar
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36782257500
Researcher ID
ELA-9787-2022

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Formation of bio-based derived dicalcium silicate ceramics via mechanochemical treatment: physical, XRD, SEM and FTIR analyses

2023-07 , Siti Nur Hazwani Yunus , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , Nur Hazlinda Jakfar , Cheng Ee Meng , Emma Ziezie Mohd Tarmizi , Zainal Abidin Talib

Beta-dicalcium silicate plays an important role in modern technology, but its tendency for polymorphic transformation results in the dusting phenomenon, is a major challenge. Therefore, mechanochemical treatment is used to reduce the particle size to retain the stability of the polymorph. In this study, pure dicalcium silicate ceramics of β-monoclinic structure with P 121/c1 space group were synthesized using calcium oxide and silicate powders derived from calcined eggshells and rice husks, respectively. The powders were mixed in a 2:1 molar ratio by mechanochemical treatment and heat-treated in the air at temperatures ranging from 900°C to 1100°C for 2 h. The results reveal that pure betadicalcium silicate formed at 1100°C without adding stabilizers. The properties of the pristine and sintered bodies were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). SEM revealed that the grain and pore sizes increase with rising sintering temperatures. FTIR spectra indicate the existence of Si-O bonds in -4 4 SiO tetrahedrons on all the samples. The sample sintered at 1000°C attains the lowest bulk density (1.2463 g/cm3), whereas the apparent porosity is the highest (62.5%). The reason for this trend is due to the decomposition of carbonate into CO2 gas. The densification onset for the sample sintered at 1100°C as the bulk density rises and grain size achieves 6.06 μm. This study further explains the effect of sintering temperatures on the physical, structural, and morphological properties of Ca2SiO4 which would also be useful for further optimization of its use.

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Synthesis of sustainable binary Calcium monosilicate ceramics from bio-waste: effect of sintering temperature on microstructure and electrical properties

2023-01 , N. H. Jakfar , Khor Shing Fhan , Banjuraizah Johar , Nur Maizatul Shima Adzali , S. N. H. Mohd. Yunus , Cheng Ee Meng , E. Z. M. Tarmizi , Z. A. Talib

This study was conducted to synthesise calcium monosilicate ceramics using rice husks and raw eggshells and investigated the effect of sintering temperature on the physical, microstructure and electrical properties of the final product. The high content of calcium and silicon in eggshells and rice husks, respectively promote the use of waste materials in the production of calcium monosilicates by mixing in a molar ratio 1CaO:1SiO2 and fired at different sintering temperatures for 2 hours with a heating rate of 10°C/min. A good correlation between sintering temperature, structural, microstructure, and electrical properties of calcium silicate was observed. The structural and morphological evolutions were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX). XRD analysis showed that the main crystalline phases of synthesised calcium monosilicate are pseudowollastonite (ICSD 98- 005-2598) at 1250°C, and the phases of SiO2 also exist in different types of minerals. Besides, a small amount of larnite, Ca2SiO4 was traced at 1100°C and 1200°C. Fourier Transforms Infrared (FTIR) spectra showed the presence of characteristic functional groups in the precursor powder. In Nyquist plots, the summit frequency of the dominant arc decreases with increasing sintering temperatures. It may be attributed to the co-effect of the grain size and pore. A larger value of impedance at a lower frequency suggests an essential role of boundaries in governing the electrical properties of the sintered ceramics. As the sintering temperature increases, the microstructure of the sintered samples becomes denser while conductivity performance decreases. This is due to the reduction of particle interfaces and charge transfer.

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