Crystallisation of processed nepheline syenite–magnesite glasses

Abstract

Transparent glasses were prepared from processed nepheline syenite–magnesite mixtures. Incorporation of TiO₂ in the base glasses changes the glass colour from white to amber or dark brown. Translucent porcelainous glass ceramics with white, creamy and a variety of bluish colorations were obtained in glasses containing non-magnetic nepheline syenite. However, dark marblelike glass ceramics were developed in glasses containing middling and tailing nepheline syenite. Aluminium diopside [Ca(Mg,Al)(Si,Al)₂O₆], nepheline, forsterite, magnesium titanate MgTi₂O₅ and hematite were developed by heat treatment of these glasses. SEM micrographs tend to show fine and uniform bulk with increasing Fe₂O₃ contents in the parent glass ceramic samples, however addition of TiO₂ enhances nucleation and the microstructure becomes of evenly good uniform fine structure in the sample with lowest iron content.

Keywords:

• GLASS CERAMIC
• MICROSTRUCTURE
• NEPHELINE SYENITE
• OLIVINE
• PYROXENE