resumo
The aim of this study was to investigate the effects of different nucleating agents (P2O5, TiO2 and ZrO2) on the crystallization behaviour and the properties of a parent glass with composition 23.7 Li2O-2.63 K2O-2.63 Al2O3-71.78 SiO2 (mol%) and SiO2/Li2O molar ratio far beyond that of stoichiometric lithium disilicate (LD, Li2Si2O5). The scanning electron microscopy examination of the as-cast non-annealed glasses revealed the occurrence of liquid-liquid phase separation for all the compositions. P2O5 revealed to be effective in promoting bulk crystallization of LD, while TiO2 and ZrO2 led to surface crystallization. Moreover, ZrO2 enhances the glass polymerization and shifts T-p to higher temperatures, hindering crystallization. At 900 degrees C, TiO2-containing glasses feature LD and lithium metasilicate (LMS, Li2SiO3), while P2O5- and ZrO2-containing ones present monophasic LD and LMS glass-ceramics, respectively.
palavras-chave
ALUMINOSILICATE GLASS; SILICATE-GLASSES; CRYSTAL NUCLEATION; THERMAL-ANALYSIS; LI2O-SIO2 GLASS; CERAMICS; SYSTEM; KINETICS; PHASES; AL2O3
categoria
Materials Science
autores
Fernandes, HR; Tulyaganov, DU; Ferreira, JMF
nossos autores
Hugo Alexandre Gonçalves da Rocha Fernandes
Investigador Júnior
José Maria da Fonte Ferreira
Professor(a) Jubilado(a)Grupos
G3 - Materiais Eletroquímicos, Interfaces e Revestimentos
G5 - Materiais Biomiméticos, Biológicos e Vivos
agradecimentos
Hugo R. Fernandes thanks FCT for the PhD grant (SFRH/BD/41307/2007). All authors are grateful for the financial support from CICECO.