Lithium Disilicate Bioceramic Obtained from Alternative Silica Source, the Rice Husk

摘要

The crystallization process of lithium disilicate glass-ceramic with SiO_2 from rice husk silica replacing the high-purity SiO_2 starting powder has been investigated in this work. Glasses were developed at the stoichiometric composition of 66%.molSiO_2:33%.molLiO_2 using commercial SiO_2 and the one obtained by thermochemical treatment of rice husk. The influence of rice husk-SiO_2 on crystallization process to different granulometry, microstructure and kinetic behavior was determined and discussed. Investigations were carried out by means of differential thermal analysis (DTA), X-ray fluorescence (XRF), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Amorphous and transparent glasses were obtained after melting. The lithium disilicate glass-ceramic crystallization peaks (Tp) are between 550 to 660°C to different granulometry (<63μm, 63μm < x < 250μm and lmm < x < 2mm) and DTA heat rates (5; 10; 15; and 20°C/min) in both glasses from different silica sources, and the formed phase was Li_2Si_2O_5 as the crystalline phase after DTA thermal analysis as XRD confirmation. Improve in mechanical properties were estimated by morphological analysis of the microstructure modification in increasing the heat treatments temperature by SEM. The increase of glass substitution for crystalline phase was also observed with SEM images to both glass-ceramics from different silica sources.