Papers by Author: Erika Davim

Abstract: The crystallization process of lithium disilicate glass-ceramic with SiO₂ from rice husk silica replacing the high-purity SiO₂ starting powder has been investigated in this work. Glasses were developed at the stoichiometric composition of 66%.molSiO₂:33%.molLiO₂ using commercial SiO₂ and the one obtained by thermochemical treatment of rice husk. The influence of rice husk-SiO₂ 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 1mm < 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 Li₂Si₂O₅ 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.

Abstract: This paper reports a preliminary study on the development and characterization of a porous calcium phosphate glass-ceramic for tissue engineering application. To obtain porous glass scaffolds, a mixture of 3CaO.P2O5-SiO2-MgO glass (grain size below 20 'm) and NaCl with 200- 300 'm of particle size was taken in the volume proportion 1:1. The mixture was shaped into cylindrical samples (10 mm diameter x 10 mm thick) by using unidirectional pressing. The sintering thermal cycle was selected by means of thermal analyses (DTA/TG and dilatometry) in order to attain a high enough cohesion among the glass particles. After thermal consolidation, the salt was dissolved in water, resulting in highly porous materials. The effect of the sintering thermal cycle on the structure and microstructure characteristics of the scaffolds was investigated in this paper.