Tribology and Materials | Volume 5 | Issue 1 | 2026 | 38-49
|
https://doi.org/10.46793/tribomat.2026.006
|
|
Combined mechanical mixing and hydrothermal synthesis of gehlenite-based ceramics
Auns Qusai Hashim Al-Neami
1,
Hasnaa Shareef Ahmed Jolak1,
Ayad Murad Takhakh1,
Fadhil Kareem Farhan2
1 College of Engineering, Al-Nahrain University, Baghdad, Iraq
2 College of Science, Al-Karkh University of Science, Baghdad, Iraq
Abstract: Gehlenite-based ceramics in the CaO-Al2O3-SiO2 calcium aluminosilicate (CAS) system were synthesised using a combined approach that integrates hydrothermal treatment with mechanical mixing. Three formulations with varying CaO:Al2O3:SiO2 ratios were prepared to investigate phase development. The precursor powders were first mechanically mixed in water and subjected to hydrothermal reaction at 200 °C for 48 h, then calcined (1000 °C) and sintered (1200 − 1250 °C) into dense pellets. X-ray diffraction (XRD) analysis confirmed the formation of gehlenite (Ca2Al2SiO7) as the major phase, with minor secondary phases (wollastonite, corundum and cristobalite) noticeable at 1200 °C. Notably, at 1250 °C, the gehlenite reflections intensified, indicating more complete crystallisation. Scanning electron microscopy (SEM) revealed a fine microstructure of submicron particles (0.4 − 0.8 µm) agglomerated into a porous network. Energy-dispersive X-ray spectroscopy (EDS) showed elemental compositions in close agreement with the nominal stoichiometry (within approximately 3 wt. % for Ca, Al and Si), confirming homogeneous mixing. The combined hydrothermal-mechanical route produced gehlenite ceramics at a sintering temperature (approximately 1250 °C) lower than conventional solid-state methods, achieving high phase purity and uniform microstructure. The enhanced phase formation is attributed to improved precursor reactivity and nucleation from the hydrothermal step. This approach offers a viable pathway to fabricate CAS engineering ceramics with controlled crystallinity and porosity for potential high-temperature and structural applications.
Keywords: gehlenite, hydrothermal, mechanical mixing, sintering temperature, ceramics.
Received: 12-09-2025, Revised: 10-12-2025, Accepted: 28-12-2025
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt,
and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.
2 College of Science, Al-Karkh University of Science, Baghdad, Iraq
Abstract: Gehlenite-based ceramics in the CaO-Al2O3-SiO2 calcium aluminosilicate (CAS) system were synthesised using a combined approach that integrates hydrothermal treatment with mechanical mixing. Three formulations with varying CaO:Al2O3:SiO2 ratios were prepared to investigate phase development. The precursor powders were first mechanically mixed in water and subjected to hydrothermal reaction at 200 °C for 48 h, then calcined (1000 °C) and sintered (1200 − 1250 °C) into dense pellets. X-ray diffraction (XRD) analysis confirmed the formation of gehlenite (Ca2Al2SiO7) as the major phase, with minor secondary phases (wollastonite, corundum and cristobalite) noticeable at 1200 °C. Notably, at 1250 °C, the gehlenite reflections intensified, indicating more complete crystallisation. Scanning electron microscopy (SEM) revealed a fine microstructure of submicron particles (0.4 − 0.8 µm) agglomerated into a porous network. Energy-dispersive X-ray spectroscopy (EDS) showed elemental compositions in close agreement with the nominal stoichiometry (within approximately 3 wt. % for Ca, Al and Si), confirming homogeneous mixing. The combined hydrothermal-mechanical route produced gehlenite ceramics at a sintering temperature (approximately 1250 °C) lower than conventional solid-state methods, achieving high phase purity and uniform microstructure. The enhanced phase formation is attributed to improved precursor reactivity and nucleation from the hydrothermal step. This approach offers a viable pathway to fabricate CAS engineering ceramics with controlled crystallinity and porosity for potential high-temperature and structural applications.
Keywords: gehlenite, hydrothermal, mechanical mixing, sintering temperature, ceramics.
Received: 12-09-2025, Revised: 10-12-2025, Accepted: 28-12-2025
|
|
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt, and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.