Effect of replacing calcium oxide with calcium fluoride on some physical properties of borosilicate glass ceramics

Abstract

Two glass samples were prepared according to the molar formula (20%X–40%B2O3–40%SiO2), where X = CaO or CaF2. The glass was melted at 1300°C for 3 h until homogenous glass was obtained. The glass samples were heat-treated at 700°C for 2 h and at 850°C for different times. The green glass obtained has low dielectric constant and positive magnetic susceptibility. The molar volume, scanning electron microscope and differential thermal analysis studies showed that the crystallization rate increases with an increase in the sintering time. The replacement of CaO by CaF2 improves the physical properties of the glass. The existence of fluorine ions increases the electrical conductivity, magnetic susceptibility, molar volume, dielectric constant and effective overall reaction rate (κ). All measured properties have a random behaviour with sintering time due to phase separation and asymmetry of crystallization.

Nanocrystallization of CaF2 from Na2O/K2O/CaO/CaF2/Al2O3/SiO2 Glasses

“…Here, the crystallization of fluoroapatite, fluoromica, and related structures as well as the general effect on nucleation is reported. In many systems addition of fluoride to the glass enhances nucleation. , This effect has also been described in the case of CaF 2 . This paper presents a study on the crystallization of CaF 2 from a glass in the system Na 2 O/K 2 O/CaO/CaF 2 /Al 2 O 3 /SiO 2 .…”

Effect of CaF2 on Interfacial Phenomena of High Alumina Refractories with Al Alloy

“…However, partial conversions could occur in the matrix probably through the formation of metastable phases [41] or loss of fluoride species from CaF 2 [42,43] during the heat treatment. The metastable conversions could be influenced by the presence of oxides in the refractory powder, although the mechanisms involved are not clear at this point.…”

Preparation and characterization of vitrified glass matrix for high level waste from MOX fuel processing

“…Along with waste oxide loading, the Al 2 O 3 , ZrO 2 and MoO 3 contents of the glass matrix increased. Although these oxides are known to increase the processing temperature, their influence was partially neutralized due to the increasing fluoride content which acts as fluxing agent [14]. Presence of fluoride along with oxides of sodium and aluminium in a glass melt is similar to addition of cryolite (Na 3 AlF 6 ).…”