Sol-gel synthesis of GTSA ceramic beads via calcium-alginate templating

초록

In this study, GeO2-transition metal oxide-SiO2-Al2O3 composite ceramic beads are successfully synthesized via a sol-gel process using calcium alginate as a sacrificial template. The effects of key processing parameters on the structural and mechanical properties of ceramic beads are systematically investigated. The specific parameters examined include NaAlg concentration (0.5-2.0 wt%), CaCl2 concentration (0.1-0.7 M), curing time (0-60 min), and sintering temperature (900 degrees C-1200 degrees C). Optimal spherical-bead formation is achieved at 1.5 wt% NaAlg, where the balance between surface tension and viscosity enable stable droplet formation, based on the Rayleigh-Plateau instability theory. The ionotropic gelation mechanism involving Na+ <-> Ca2+ ion exchange is quantitatively confirmed via energy-dispersive X-ray spectroscopy analysis. Thermal analysis indicate complete organic template removal above 900 degrees C and the formation of complex oxide phases. The sintered beads exhibit densities ranging from 1.66 to 2.18 g/cm3 and compressive strengths of 0.14-6.47 MPa, with optimal properties achieved at 1100 degrees C. Controlled porosity up to 49 % is achieved through starch incorporation.

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