Nucleation and crystallization of Ba2Si3O8 spherulites in a barium aluminum silicate glass, and mechanical properties of the obtained glass-ceramics

Abstract

The effect of spherulitic crystallization on the elastic moduli and fracture toughness of a barium aluminum silicate glass was investigated. The crystallization process results in Ba2Si3O8 phase and is initiated from Ba rich nuclei. Nucleation is optimal in the 690-720 °C interval. Young's modulus is increased by 12.5% when the glass-ceramic conversion is nearly complete. Nevertheless, as the size and the volume fraction of crystals are increased, some microcracking shows up upon cooling from the crystallization temperature. An optimal improvement of the fracture toughness (SEPB method) by 27 % is observed for a 49 % volume fraction of 5 to 10 m large spherulites.

Toughening of soda-lime-silica glass by nanoscale phase separation: Molecular dynamics study

“…This is exploited in glass-ceramics which are toughened due to the presence of crystallites embedded in the glass matrix [7,8]. Glass-ceramics are typically produced by a controlled twostep heat treatment to induce nucleation and crystal growth [9]. Crystallization often leads to a loss of transparency, but it can be avoided if the size of the crystallites is much smaller than the wavelength of visible light or the refractive indexes of glass and crystal are similar and the crystal possesses low birefringence [10].…”

Fabrication of magnetically controllable glass ceramics with completely dense microstructure by hot pressing

“…In addition, the introduction of hot pressing can also avoid the problems of low densification degree and the presence of uncontrollable crystalline phase in glass ceramics as that obtained by powder-sintering method. 7,[19][20][21][22][23][24][25][26] The motivation of this study is that the traditional preparation method of magnetic glass ceramics has the disadvantages of uncontrollable amount and grain size of magnetic phase, uncontrollable type of crystalline phase, and low densification degree. 7,[19][20][21][22][23][24][25][26] In this study, by introducing hot pressing method and adjusting the ratio of magnetic phase to glass phase, magnetically controllable and completely dense glass ceramics can be obtained.…”

“…7,[19][20][21][22][23][24][25][26] The motivation of this study is that the traditional preparation method of magnetic glass ceramics has the disadvantages of uncontrollable amount and grain size of magnetic phase, uncontrollable type of crystalline phase, and low densification degree. 7,[19][20][21][22][23][24][25][26] In this study, by introducing hot pressing method and adjusting the ratio of magnetic phase to glass phase, magnetically controllable and completely dense glass ceramics can be obtained. The effects of sintering conditions and Fe 3 O 4 contents on the densification, physical, and magnetic properties of final samples were studied.…”

“…Therefore, it may be feasible to prepare glass ceramics with controllable magnetic properties by hot pressing the mixture of glass and Fe 3 O 4 powder. In addition, the introduction of hot pressing can also avoid the problems of low densification degree and the presence of uncontrollable crystalline phase in glass ceramics as that obtained by powder‐sintering method 7,19–26 …”