Abstract
Glass-ceramic materials were obtained by heat treatment (960 ºC for 2, 4, and 6 hs) of glasses with CaCO3 47.50 wt%-TiO2 23.75 wt%-SiO2 23.75-Al2O3 5.00 wt% formulation produced by the melt-quenching technique (melting at 1650 ºC and subsequent annealing at 650 ºC). The materials’ structural characterization and crystallization kinetics (Kissinger method) indicate the presence of CaTiO3, CaSiO3, and CaTiSiO5 crystalline phases with activation energies 217, 281, and 446 kJ/mol, respectively. The structure refinement (Rietveld method) suggests metastability for the CaSiO3 and CaTiSiO5 phases as a function of the heat treatment time. The increase in time favors CaTiO3 crystallization, from 62.97 wt%, in the 2 hs treated sample, to 79.21 wt%, in the 6 hs treated sample. EDS and microstructure analyses confirm the glass-ceramic production and indicate segregation of the CaTiO3 phase for longer heat treatment times.
Highlights
Glass-ceramic materials are usually defined as materials with crystalline structures (0.5 to 99.5 wt%) embedded in a non-crystalline matrix[1]
Glass samples of the CaO 47.50 wt%-TiO2 23.75 wt%SiO2 23.75-Al2O3 5.00 wt% system were obtained by the melt-quenching technique (1650 oC)
There was a small deviation from the proposed formulation due to diffusion of Al from the crucible to the melted precursors: CaO 46.234 wt%-TiO2 22.225 wt%-SiO2 22.853Al2O3 8.034 wt%-contaminants 0.564 wt%
Summary
Glass-ceramic materials are usually defined as materials with crystalline structures (0.5 to 99.5 wt%) embedded in a non-crystalline matrix (glassy phase)[1]. Stookey and since have been extensively studied Research interest in these materials can be mainly attributed to their low apparent porosity, reduced thermal expansion coefficient and low water absorption, characteristics that can be associated with further desirable properties[2]. They lend themselves to large scale production via any traditional technique aimed at the synthesis of glassy materials, such as the melt-quenching technique, being an attraction for the industrial sector[3]
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